Implement a proc-macros threads creation

[d3zd3z]

Replace how Zephyr threads are declared in Rust. Provides a proc-macro to make this fairly straightforward:

#[zephyr::thread(stack_size = MY_STACK_SIZE)]
fn my_thread(arg1: u32, arg2: MyType) { ... }

This function can then be called, and will return a ReadThread. This has methods for setting priority, and a start method, which returns a RunningThread, which has a join method. The thread can be respawned after it has exited.

The thread macro also accepts a pool_size = nnn parameter, which will create an array of threads, and can be started that many times.

[teburd]

I like it

[cfriedt]

It would be smart to allow a timeout and return the integer result.

[cfriedt]

Actually, would it make more sense to do something similar to what std::thread does where we return a Result that can be either Ok or an Err? I guess that's more "rustonic" than integer return values 😅

[d3zd3z]

I think handling the timeout is a reasonable request. The Result will be Rust-y. But, thinly wrapped.