Rust module support

[jnippula]

Basic Rust module build support

Rust compiler setup
cmake support for px4 rust module creation
Dockerfile modifications for Rust build in CI
Submodules:

• PX4/Nuttx adaptation library for Rust modules (rust_px4_nuttx)
  • Alloc (for String, vector, etc)
  • Basic rust logger support
  • nuttx udp socket send and recv
  • hrt_timer support
• Simple example app (rust_module_example)

[jnippula]

Now added the rust module support into the existing cmake/px4_add_module.cmake file, rust module can be configured in cmakelists file like that:

px4_add_module(
	MODULE modules__rust_module_test
	MAIN rust_module_test
	LANG Rust
	RUST_MOD
		rust_mod
	)

[jnippula]

Note, that local build env does not need any Rust build support in case there is no rust module enabled in defconfig file. So no local env changes needed for those developers who don't work with rust components.

[jnippula]

Rust parts moved to separate repos and added as submodules