Add Support for "Main Out", "Phones" and "Blend" knobs.

[kbjdad]

Please add support for the "Main Out", "Phones" and "Blend" knobs:

[oddbear]

New beta release:
https://github.com/oddbear/Revelator.io24.Api/releases/tag/v0.0.2-streamdeck-beta

Support added, but not with dB scale for now... just percentages.