Timers runtime isr binding

[bjoernQ]

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Submission Checklist 📝

• I have updated existing examples or added new ones (if applicable).
• My changes were added to the CHANGELOG.md in the proper section.

Extra:

• I have read the CONTRIBUTING.md guide and followed its instructions.

Pull Request Details 📖

Description

This implements runtime ISR binding for SYSTIMER and TIMG. It makes Systimer's DelayNs implementation available when the async feature is active.

Two new examples are added

• embassy_systimer_delay.rs - uses the DelayNs implementation
• embassy_hello_world_systimer.rs - same as embassy_hello_world but using the systimer time-driver (not for ESP32 or ESP32-S2), I added it since we currently don't check that driver (and also to test my changes)

Testing

Running the existing (adapted) examples and added examples

[JurajSadel]

LGTM, thanks! I left a stupid nitpick :D
I didn't test all examples on all targets though, I tested new ones and randomly picked a few others.

[jessebraham]

Sorry for taking so long for getting to this. I think most of my concerns have been resolved in the meantime, so for the sake of getting this merged LGTM!

[jessebraham]

Looks like the HIL tests need updating