Feature: Show Volume on Screen about openrtx

[n1zzo]

This is particularly relevant for the T-TWR plus where no dial is present, thus there is no way to get the current volume level.

I would add another thin bar on top of the squelch one, personally I don’t fancy much the idea of a modal screen that takes away the attention from the main UI just to communicate a single number.

[marcoSchr]

This is an example of how it could look with a bar in the bottom.
First image is with a small screen, second image is with a large screen.