- 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
- Cleaned up comments in implementations of `IInferenceParams`
- Removed default values for all parameters in `LLamaContext.Sample` - they're never used and probably _shouldn't_ ever be used