[Feature] Predefined LED's in ESP-IDF configuration tool?

[JoeyStrandnes]

Predefined LED's?

Got this idea when I was messing about with LED timings in Issue #13 and found it somewhat useful to have predefined LED timings instead of having to write them down somewhere else. This is a small detail since most WS28xx LEDs have similar timing specs but it might still be useful to easily ensure that all LEDs operate within the proper specifications.

I forked your repo and made the necessary changes to implement such a thing.
Also added a range limitation on the RMT channel configuration, the help text states "Defines that RMT Channel that will be used to modulate the signal. Valid values are defined by enum rmt_channel_t (0-7)" but the input data field is not sanity checked. Limited the input to channel 0-7.

Tested the code on an ESP32 and WS2812B and it works fine.
Below is a demo video of the esp-idf configuration tool with the predefined LEDs.

The README.md is also adjusted, it was never updated when migrating the code to the esp-idf configurator.

NOTE: The timings should be double checked, I don't own all of the LEDs so I'm unable to test them.

[JoeyStrandnes]

Made minor changes to prevent users from selecting multiple LEDs and screwing up the timings.
The code is tested on an ESP32 with WS2812B LEDs.

Reason for not creating a pull request is that it needs more testing with other LED types and It makes a somewhat big change that should probably be looked at by others.