embassy: introduce InterruptExecutor::spawner()

[kaspar030]

This PR adds InterruptExecutor::spawner() to match the corresponding change to embassy.

Must

• The code compiles without errors or warnings.
• All examples work.
• cargo fmt was run.
• Your changes were added to the CHANGELOG.md in the proper section.
• You updated existing examples or added examples (if applicable).
• Added examples are checked in CI

Nice to have

• You add a description of your work to this PR.
• You added proper docs for your newly added features and code.

[kaspar030]

I think the linting issue is unrelated:

warning: the item `proc_macro` is imported redundantly
 --> /home/runner/work/esp-hal/esp-hal/esp-hal-procmacros/src/interrupt.rs:1:18
  |
1 | use proc_macro::{self, TokenStream};
  |                  ^^^^ the item `proc_macro` is already defined here
  |
  = note: `#[warn(unused_imports)]` on by default

edit yup, looks like #1210.

[MabezDev]

Thanks! This is a nice addition. I'm sorry but we just merged some other PRs which has introduced a conflict, would you mind rebasing?

[jessebraham]

I've resolved the conflict, so this LGTM. Thanks for the contribution!

(We're having some CI issues, clippy-riscv will fail, that's fine!)