Add the White channel calibration to the JSON API

[t3rral33t]

Feature request

What problem does this feature solve?

I would like to be able to adjust the white channel calibration from the JSON API so I can automate whether I have warm white or cool white. I am running the sk6812 in warm white (I know it's not recommended) because I have warm white led strips and bulbs everywhere else in my home. However when I match the screen I turn the blue channel down and it works well enough for me.

What does the proposed API look like?

How should this be implemented in your opinion?

Just add a section in the JSON API that handles white channel calibration.

Are you willing to work on this yourself?

Sure.