Implement binding via source generators and remove the current method

[Rohansi]

Binding works nicely as-is but kind of sucks for performance now. Both of the current methods (reflection and reflection emit) cannot take advantage of performance oriented features in the latest C#.

Only issue is we lose the ability to bind things dynamically but that's a tiny use case. I'd prefer only source generators to clean up code.

[Rohansi]

Added benefit to this is we can revisit the interface for binding C# functions to Mond to improve performance in that area. Preferably making it not require copying or allocating things.