Async Stateless Executor

- Added a "spinner" to the `StatelessModeExecute` demo, which spins while waiting for the next token (demonstrating that it's not blocked).

Extensions Method Unit Tests

- Removed unused `AddRangeSpan` extension

fix opaque GetState (fixes #176)

make InferenceParams a record so we can use `with`

CPU Feature Detection

MacOS default build now is metal llama.cpp #2901

Remove non-async

Coding assistent example

Removed unused properties of `InferenceParams` & `ModelParams`

SemanticKernel API Update

skip_empty_tokenization

better_instruct_antiprompt_checking

llama_get_kv_cache_token_count

Metal depends on this file to execute, and MacOS llama.cpp defaults is now METAL.

See on Mac OS enable Metal by default #2901

`GetState()` fix

Removed `GenerateResult`