Add macros for including generated C++ and Python bindings

[johanpel]

Generated bridge crates currently repeat module wrappers, include! calls, and lint attributes.

Add a small target-side crate exposing helpers such as:

quent_bindings::include_cpp_bridge!(bridge);
quent_bindings::include_instrumentation!(instrumentation);
quent_bindings::include_python_bridge!();

The C++ and instrumentation macros should accept a Rust module name so multiple generated modules can coexist. The Python module name should remain configured through the generator options.

Also see: #638 (comment)