Add Silabs drivers and examples

[silabs-szabog]

Initial Silabs Wireless Gecko Series 2 support for simpleFOC:

• PWM driver up to 6 channels
• Current Sense driver (low-side shunt) synchronized to the PWM by hardware and using DMA

Silabs Arduino Core supports the next boards: https://github.com/SiliconLabs/arduino

[runger1101001]

This is amazing, thank you so much for this big contribution!

I'm just running the tests, but if there are no objections on your part I would love to merge it to dev and then make it part of the next release.

[MarkWendler]

@runger1101001 Thanks a lot for the review!
We are glad the 2.3.6 release as target! Will you add the build/test badge for the new target to the readme.md?

We are wokring on some other features, but not for this pull request scope:

1. Updating documentation (docs repo)
2. Create Bluetooth stack and simple FOC demo (Probably hosted in a separated repo)

Objections for this pull requests are done. We are OK to merge.

[runger1101001]

Thanks so much! I have now merged it.

[silabs-szabog]

@runger1101001 Thank You!