FixedSizeQueue:
 - Enqueue would always stop one short of filling the capacity
 - Fill would only _replace_ existing items. It was only used in a place where there were not existing items! Removed the method entirely.

LLamaGrammarElement:
 - Converted into a `record` struct, removed all of the (now unnecessary) equality stuff.

- Built a new (hacky) `Detokenize` method which handles this

- Minor changes to cleanup some of the compiler warnings

- Deleted `NativeInfo` (internal class, not used anywhere)

The biggest single change is renaming `LLamaModel` to `LLamaContext`

Document interfaces