feat: optionally generate Rust bindings during build process

[ahlinc]

• Reimplements and closes Generate bindings during build #1524

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Motivation

This is required for a future work on making C lib to have an optional feature to have zero dependencies even from libc and to resolve issues with wasm32-unknown-unknown target for a Rust binding -> C lib use case on the wasm32-unknown-unknown target.

The bindgen dependency is optional and it can be used as:

cargo build -p tree-sitter -F bindgen

Because all optional dependencies automatically become features with the same names.