embassy-nrf: Make PWM drivers more flexible

[de-vri-es]

This PR:

• Derives more traits for public structs in the PWM module.

• Allows you to set the idle state of pins for when the PWM is stopped.

  From the nRF9160 manual:
  

• Allows you to configure the pins in the constructor of SimplePwm to avoid glitches on the output levels during initialization (in fact, you can now configure the whole PWM peripherals, same as with the Sequencer struct).

• Exposes bit 16 of the duty cycle value in SimplePwm in a DutyCycle struct so you can use inverted polarity.

• Adds a function to set all channels of a SimplePwm at once, to avoid doing four DMA transfers when one would have been enough.

Tested with an nRF9160.

[de-vri-es]

Is this a good way forward? It's a breaking change as it is now. I think it's nicer this way since it will be a more consistent API. But if desired I can avoid breaking the API by adding new functions instead of modifying existing ones.

[lulf]

I like the API, nice work! 🚀 It'll make my nrf54 PR harder to merge 🥲 but i'll rebase once this is merge :)

[de-vri-es]

Haha, thanks :)