Crossfire: add barometer altitude sensor

[raphaelcoeffic]

Until now, Crossfire was only allowing for altitude as part of the GPS sensor. This PR adds barometer support as well.

See betaflight/betaflight#11070.

[pfeerick]

Oh, nice... so that should end the Matek trickery where they shove the barometer into the GPS packet? :)

I find it funny that it was "tested with FreedomTX v1.32", yet the additional sensor is nowhere to be found! You'd think it would be added it if it was in the protocol, no?🤦

https://github.com/tbs-fpv/freedomtx/blob/23f9fb42e0d26935f146bbb76ca5911dbc303acb/radio/src/telemetry/crossfire.cpp#L28-L60

[raphaelcoeffic]

As it seems, this PR is missing decoding VSpeed which is packed into the same packet on 8-bit using the following packing function (x is in cm/s):

[JimB40]

I find it funny that it was "tested with FreedomTX v1.32", yet the additional sensor is nowhere to be found! You'd think it would be added it if it was in the protocol, no?

Are you using 6.13+ FW?

[pfeerick]

No, that is nothing to do with the crossfire firmware (and would be hard to do since I don't have or use crossfire at all). I was referring to the "tested with FreedomTX v1.32" that was made in betaflight PR. And the lack of the sensor being defined in the firmware... which is sort of necessary for it to work.

[raphaelcoeffic]

Just as a note for now: after discussing with all parties involved, it has been agreed to drop the third byte with VSpeed as this is redundant with the already existing sensor.