Add webui for backpack binding phrase management (like ExpressLRS TX/RX)

[pitts-mo]

I desire the ability to manage the backpack VRx Binding Phrase / UID similar to the webui of a normal ExpressLRS device.

Reasoning: I like to keep firmware files generic in order to help friends update at the field AND still have my TBS Fusion backpack preserve it's binding after I power up my HDZero goggles into a non analog module mode three times (HDZ v2 "Auto" AnalogRX power).

[pitts-mo]

Please find @CapnBry's expresslrs PR #2542 for reference :-)

ExpressLRS/ExpressLRS#2542