Add feature for CRSF RX binding via cli or vehicle_command

[benjinne]

Describe problem solved by the proposed feature

Add ability to bind CRSF receivers from flight controller

Example code was introduced in betaflight:
betaflight/betaflight#13119

Describe your preferred solution

Add CLI or UI method to bind CRSF receivers

Describe possible alternatives

n/a

Additional context

No response

[dagar]

Is this officially documented anywhere?

[benjinne]

Is this officially documented anywhere?

Sort-of in the ELRS documentation:
https://www.expresslrs.org/quick-start/binding/#updated-binding-procedure-since-expresslrs-340

[benjinne]

I've opened a PR but don't have hardware to test. If anyone wants to give a try and verify it works, we can merge it in