HAL for interrupt setup

[wavexx]

We currently have to include <avr/interrupt.h> to setup the interrupts, which is not portable.
Some minimal HAL for interrupts would avoid having to include AVR-specific parts in the code.

[leptun]

Can’t really setup interrupts in c++ directly. We probably need to use macros for defining interrupts.

[wavexx]

I think that's fine. But we need something, otherwise we have to use ifdefs when we setup interrupts for AVR. I'm trying to setup the motion ones, and I had to add several because the same code is also built for the tests, and there you don't ISR(), or the __vector definitions either.

[wavexx]

On the PC it might simply expand to nothing, just so that it builds. Not sure if @DRracer has better ideas.

[github-actions]

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