fix(crsf): assign GPS Alt unique name rather than share Baro Alt

[Allain18]

With the release of Betaflight 2025.12, CRSF now transmits two different altitude values:

• GPS altitude in the GPS frame (0x02)
• Barometric altitude (and vertical speed) in the new frame (0x09)

Currently, both of these values are displayed as "Alt" in EdgeTX, which makes it impossible to distinguish between them, even though they represent different data sources and have different characteristics (barometric altitude is in cm or dm while GPS altitude is only in m).

With this PR, the telemetry data related to the GPS altitude is displayed as "GAlt" while the barometric altitude is displayed as "Alt"

Fixes #5852

Summary of changes:

• Change ALT to GPSALT

Tested on a RM Pocket

[mha1]

Welcome to the club. Yes, this is a pain especially if you are trying to use Alt in a calculated distance sensor. You are getting offered two Alt sensor without knowing which one is AGL Altitude (Baro Alt) or MSL Alt (GPS Alt). Good luck dude, the community will eventually succeed. I hope it's you. For context, there's most likely more:

@JimB40's proposal Jan 2025: #5852

My proposal in Sep 2023: #4010

[3djc]

We also need to rename STR_SENSOR_GPSALT to STR_SENSOR_GALT for consistency

[Allain18]

STR_SENSOR_GPSALT is also used by other telemetry protocols, so it also needs to be renamed there, but it's a possibility.

The other is to create a new name like STR_SENSOR_BALT for the baro altitude and display BAlt for example.

[3djc]

I'll take care of the renaming

[philmoz]

We also need to rename STR_SENSOR_GPSALT to STR_SENSOR_GALT for consistency

Why?
The name of the string does not have to be the string value. IMO having a more meaningful string name is more useful.
Many of the other sensor string names are very different to the string value (having more understandable names).

[pfeerick]

Indeed. STR_SENSOR_GPS_ALT and STR_SENSOR_BARO_ALT make more sense IMO than STR_SENSOR_BALT and STR_SENSOR_GALT.

[pfeerick]

Yes, this is a pain

Indeed, and quite silly they clashed in the first place given you can rename it... we know one is of type GPS_ID, and the other is of type BARO_ALT_ID, so why wouldn't default name wouldn't ensure to prevent clashes? Derp! Sorry I didn't see your last comment at the time otherwise I would have pushed that back up.