VTx Band - Now numbers instead of Letters

- Use LUA 1.7.0
- Go to VTx settings
- BAND: Scroll all bands and you'll find U;1;2;3;4;5 instead of A;B;E;F;R.

Having numbers instead of letters is way less intuitive

Reproduce the issue with Lua 1.7.0 by opening VTx settings and scrolling through BAND values. Locate the script entry that renders these labels and update the behavior so the bands display A, B, E, F, and R instead of U, 1, 2, 3, 4, and 5; verify the result in the VTx settings.

Written by the indexing model from the issue text.