Consider how to scale the bindings

[ojeda]

Currently we only generate bindings for a fixed set of headers in rust/. However, as Rust abstractions grow, we will likely need to expand the set of headers greatly, which is unlikely to scale well in a single file.

Please note that, in general, we do not want Rust modules to be calling the C side directly (i.e. bypassing the abstractions). Thus allowing other modules to generate bindings at will may be opening the doors too much. In fact, ideally, we could enforce no bindings calls outside rust/.

If we can keep that approach, then as Rust abstractions grow, we may want to split rust/kernel/ into different crates, each declaring the set of bindings they need in a header etc. (and then either passing them all at once to bindgen or perhaps separately).

[ojeda]

Closing -- splitting the helpers was already done, and we will also split the crates.