* Support unicode emojis and remove emojify.js

This PR replaces all use of emojify.js and adds unicode emoji support to various areas of gitea.

This works in a few ways:

First it adds emoji parsing support into gitea itself. This allows us to

 * Render emojis from valid alias (😄)
 * Detect unicode emojis and let us put them in their own class with proper aria-labels and styling
 * Easily allow for custom "emoji"
 * Support all emoji rendering and features without javascript
 * Uses plain unicode and lets the system render in appropriate emoji font
 * Doesn't leave us relying on external sources for updates/fixes/features

That same list of emoji is also used to create a json file which replaces the part of emojify.js that populates the emoji search tribute. This file is about 35KB with GZIP turned on and I've set it to load after the page renders to not hinder page load time (and this removes loading emojify.js also)

For custom "emoji" it uses a pretty simple scheme of just looking for /emojis/img/name.png where name is something a user has put in the "allowed reactions" setting we already have. The gitea reaction that was previously hard coded into a forked copy of emojify.js is included and works as a custom reaction under this method.

The emoji data sourced here is from https://github.com/github/gemoji which is the gem library Github uses for their emoji rendering (and a data source for other sites). So we should be able to easily render any emoji and :alias: that Github can, removing any errors from migrated content. They also update it as well, so we can sync when there are new unicode emoji lists released.

I've included a slimmed down and slightly modified forked copy of https://github.com/knq/emoji to make up our own emoji module. The code is pretty straight forward and again allows us to have a lot of flexibility in what happens.

I had seen a few comments about performance in some of the other threads if we render this ourselves, but there doesn't seem to be any issue here. In a test it can parse, convert, and render 1,000 emojis inside of a large markdown table in about 100ms on my laptop (which is many more emojis than will ever be in any normal issue). This also prevents any flickering and other weirdness from using javascript to render some things while using go for others.

Not included here are image fall back URLS. I don't really think they are necessary for anything new being written in 2020. However, managing the emoji ourselves would allow us to add these as a feature later on if it seems necessary.

Fixes: https://github.com/go-gitea/gitea/issues/9182
Fixes: https://github.com/go-gitea/gitea/issues/8974
Fixes: https://github.com/go-gitea/gitea/issues/8953
Fixes: https://github.com/go-gitea/gitea/issues/6628
Fixes: https://github.com/go-gitea/gitea/issues/5130

* add new shared function emojiHTML

* don't increase emoji size in issue title

* Update templates/repo/issue/view_content/add_reaction.tmpl

Co-Authored-By: 6543 <6543@obermui.de>

* Support for emoji rendering in various templates

* Render code and review comments as they should be

* Better way to handle mail subjects

* insert unicode from tribute selection

* Add template helper for plain text when needed

* Use existing replace function I forgot about

* Don't include emoji greater than Unicode Version 12

Only include emoji and aliases in JSON

* Update build/generate-emoji.go

* Tweak regex slightly to really match everything including random invisible characters. Run tests for every emoji we have

* final updates

* code review

* code review

* hard code gitea custom emoji to match previous behavior

* Update .eslintrc

Co-Authored-By: silverwind <me@silverwind.io>

* disable preempt

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Add octicon SVG sprite

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Static prefix

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* SVG for all repo icons

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* make vendor

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Swap out octicons

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Move octicons to top of less imports

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix JS

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Definitely not a search/replace

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Missed regex

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Move to more generic calls and webpack

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* make svg -> make webpack

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Remove svg-sprite

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update tests

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Missed a test

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Remove svg from makefile

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Suggestions

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Attempt to fix test

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Update tests

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Revert timetracking test

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Swap .octicon for .svg in less

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add aria-hidden

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Replace mega-octicon

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix webpack globbing on Windows

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Revert

Co-Authored-By: silverwind <me@silverwind.io>

* Fix octions from upstream

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Fix Vue and missed JS function

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Add JS helper and PWA

Signed-off-by: jolheiser <john.olheiser@gmail.com>

* Preload SVG

Signed-off-by: jolheiser <john.olheiser@gmail.com>

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <matti@mdranta.net>

Created a second webpack output file for swagger-ui which is loaded on
the /api/swagger route. One notable difference is the absence of the
swagger favicon that was previously used which is now the gitea icon. I
see no easy way to restore that favicon, so I decided to not keep it.

* Upgrade lato fonts to v16

* Upgrade lato fonts to v16

* fix bug

* Add lang specific font stacks

* Force font changes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix icons

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix octicons and icons

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Just override the semantic ui fonts only

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Missed the headers... override them too

* Missed some more semantic ui stuff

* Fix PT Sans

Signed-off-by: Andrew Thornton <art27@cantab.net>

* More changes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Squashed commit of the following:

commit 7d1679e907
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 13:53:49 2019 +0100

    Remove missed YaHei leftover from _home.less

commit 0079121ea9
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 12:03:54 2019 +0100

    Fix overdone fixes (inherit, :lang)

commit 62c9199159
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 02:29:10 2019 +0100

    Fix elements w/ explicit lang (language chooser)

commit b3117587aa
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 20:17:26 2019 +0100

    Fix textarea also (to match body)

commit 81cedf2c30
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 19:41:39 2019 +0100

    Revert css temporarily to fix conflict

commit 80ff82797f
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 19:15:30 2019 +0100

    Tweak CJK, fix Yu Gothic, more monospace inherits

commit 581dceb9a8
Author: Mike L <cl.jeremy@qq.com>
Date:   Mon Mar 11 13:09:26 2019 +0100

    Add Lato for latin extd. & cyrillic, improve CJK

* update stylesheet

* Move swagger interface under /api/v1

* Update swagger-ui

* Add /api/swagger and prepare for multiple api version

* Update test links

* Fix footer link

* Cleaning up public/ and documenting js/css libs.

This commit mostly addresses #1484 by moving vendor'ed plugins into a
vendor/ directory and documenting their upstream source and license in
vendor/librejs.html.

This also proves gitea is using only open source js/css libraries which
helps toward reaching #1524.

* Removing unused css file.

The version of this file in use is located at:
  vendor/plugins/highlight/github.css

* Cleaned up librejs.html and added javascript header

A SafeJS function was added to templates/helper.go to allow keeping
comments inside of javascript.

A javascript comment was added in the header of templates/base/head.tmpl
to mark all non-inline source as free.

The librejs.html file was updated to meet the current librejs spec. I
have now verified that the librejs plugin detects most of the scripts
included in gitea and suspect the non-free detections are the result of
a bug in the plugin. I believe this commit is enough to meet the C0.0
requirement of #1534.

* Updating SafeJS function per lint suggestion

* Added VERSIONS file, per request