- Made `NativeApi` into a `static class` (it's not intended to be instantiated)
 - Moved `LLamaTokenType` enum out into a separate file
 - Made `LLamaSeqId` and `LLamaPos` into `record struct`, convenient to have equality etc

- Modified `llama_sample_token_mirostat` and `llama_sample_token_mirostat_v2` to take `ref float` instead of as a `float*`. Less pointers is always good.
 - Modified `llama_sample_repetition_penalty` and `llama_sample_frequency_and_presence_penalties` to take pointers instead of arrays. This allows the use non non allocating types (e.g. Span) instead of arrays
 - Modified higher level API to accept `Memory<int>` instead of `int[]`, which can be used to reduce allocations at call sites

- Moved repeated code to convert `LLamaTokenDataArray` into a `LLamaTokenDataArrayNative` into a helper method.
   - Modified all call sites to dispose the `MemoryHandle`
 - Saved one copy of the `List<LLamaTokenData>` into a `LLamaTokenData[]` in `LlamaModel`