Use a translator callback to convert GRB data to RMT pulses.

[docbacardi]

Fixes #3508.

• This PR is for the dev-esp32 branch rather than for the release branch.
• This PR is compliant with the other contributing guidelines as well (if not, please describe why).
• I have thoroughly tested my contribution.
• The code changes are reflected in the documentation at docs/*.

This patch replaces the custom ISR in ws2812.write with a translator callback.
Furthermore it introduces 2 small improvements:

1. If the hardware supports it, all channels in the write request are placed in a group. This moves the start of all RMT sequences much closer together. On my hardware I observed >=50ns .
2. New optional parameters can set the duration of the reset signal and the duration for the high and low phase of the 0 and 1 symbols. This allows to adapt the timings to many other RGB LEDs.

[pjsg]

This looks plausible to me -- I need to get some ws2812s attached to an esp32 to test.....

[docbacardi]

The module name might have become a little bit misleading. It is not ws2812 specific, but works with a lot of other RGB LEDs. I did my tests with a single SK6812 on the ESP32-C3 devkit. Another unknown LED strip from some home improvement store is on the way.

[HHHartmann]

But there are other led strips which will not work, so that would be as misleading.

[jmattsson]

@docbacardi @pjsg any chance of seeing what needs tweaking to make this compatible with the current IDF5 branch? I'm out of my depth with the RMT stuff.

[docbacardi]

I will try and port this. Also a good chance to move to the new RMT driver.

[docbacardi]

Please find the patch here: #3629

The migration to the new RMT code in IDF5 would affect more modules. One step after another...

[jmattsson]

Is this PR still relevant with #3629 having been merged?