Check Model Path Exists

- Checking if model is readable

Added a check for EOS token in LLamaStatelessExecutor

Tokenizer Fixes For Issue 430

- Properly displaying `LLamaToken`
 - Removed all tokenisation code in `SafeLLamaContextHandle` - just pass it all through to the `SafeLlamaModelHandle`
 - Improved `SafeLlamaModelHandle` tokenisation:
   - Renting an array, for one less allocation
   - Not using `&tokens[0]` to take a pointer to an array, this is redundant and doesn't work on empty arrays

StreamingTextDecoder Fix & Tests

Update README.md

LLamaToken Struct

Gpu layer count change

build(deps): bump xunit from 2.6.4 to 2.6.5

Bumps [xunit](https://github.com/xunit/xunit) from 2.6.4 to 2.6.5.
- [Commits](https://github.com/xunit/xunit/compare/2.6.4...2.6.5)

---
updated-dependencies:
- dependency-name: xunit
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Grammar Test (#394 repro)

Fixed example code in readme

Safer Handle Initialisation

Improved exceptions in IModelParams for unknown KV override types.

Update README.md

Release 0.9.1 (hotfix)

Test Release PR 2

Test PR

Fixed prepare_release script

Updated readme for 0.9.0 release

Fix typos in SemanticKernel README file

Fixed readme: Max -> Mac

Extra ModelParams Checking

Safer Model Handle Creation

- made `llama_backend_init` private. This is automatically called, there is no way it can correctly be used externally.
 - made `llama_token_to_piece` safe (Span instead of pointer)