* Make CertFile and KeyFile relative to CustomPath

The current code will absolute CertFile and KeyFile against the current working directory. This is quite unexpected for users. This code makes relative paths absolute against the CustomPath.

Fix #4196

* Improve error reporting when reading certificates

* Apply suggestions from code review

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Change graceful to use a singleton obtained through GetManager instead of a global.
* Graceful: Make TestPullRequests shutdownable
* Graceful: Make the cron tasks graceful
* Graceful: AddTestPullRequest run in graceful ctx
* Graceful: SyncMirrors shutdown
* Graceful: SetDefaultContext for Xorm to be HammerContext
* Avoid starting graceful for migrate commands and checkout
* Graceful: DeliverHooks now can be shutdown
* Fix multiple syncing errors in modules/sync/UniqueQueue &  Make UniqueQueue closable
* Begin the process of making the repo indexer shutdown gracefully

* Graceful: Create callbacks to with contexts

* Graceful: Say when Gitea is completely finished

* Graceful: Git and Process within HammerTime

Force all git commands to terminate at HammerTime
Force all process commands to terminate at HammerTime
Move almost all git processes to run as git Commands

* Graceful: Always Hammer after Shutdown

* ProcessManager: Add cancel functionality

* Fix tests

* Make sure that process.Manager.Kill() cancels

* Make threadsafe access to Processes and remove own unused Kill

* Remove cmd from the process manager as it is no longer used

* the default context is the correct context

* get rid of double till

Previously we could not handle graceful restarts for http over unix
sockets. These can now be handled.

* Graceful Shutdown for windows and others

Restructures modules/graceful, adding shutdown for windows, removing and
replacing the old minwinsvc code.

Creates a new waitGroup - terminate which allows for goroutines to
finish up after the shutdown of the servers.

Shutdown and terminate hooks are added for goroutines.

* Remove unused functions - these can be added in a different PR

* Add startup timeout functionality

* Document STARTUP_TIMEOUT

* Only attempt to kill parent once

* Apply suggestions from code review

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Add waitgroup for running servers

* Prevent deadlock in indexer initialisation during graceful restart

* Move from gracehttp to our own service to add graceful ssh

* Add timeout for start of indexers and make hammer time configurable

* Fix issue with re-initialization in indexer during tests

* move the code to detect use of closed to graceful

* Handle logs gracefully - add a pid suffix just before restart

* Move to using a cond and a holder for indexers

* use time.Since

* Add some comments and attribution

* update modules.txt

* Use zero to disable timeout

* Move RestartProcess to its own file

* Add cleanup routine