Unify RGB and RGBW commands (#7297)

Unify RGB and RGBW commands (#7297)

* Fix unicode in comments

Co-Authored-By: fauxpark <fauxpark@gmail.com>
* Remove separate RGBW implementation for a unified function

* Set White to 0 in RGBW LEDs

This is just to get this working, later, proper brightness can be handled elsewhere.

* Use us instead of nanoseconds(?) since it renders correctly on web

* Remove RGBW function from arm/ws2812.h

* Remove RGBW function from arm/ws2812.c

* Formatting changes

* Add doc info