move GLOBAL_POSITION_SENSOR to common

[haumarco]

With the message adjustments applied in #2422, we'd now like to follow up by moving GLOBAL_POSITION_SENSOR to common.

As a use case, we have PX4/PX4-Autopilot#26307 on PX4 upstream. We want to use it as an additional interface for auxiliary global position (AGP) sources (alongside DDS) and to display AGP data on the ground control station.

Let me know what type of tests are required.

[hamishwillee]

@auturgy @julianoes Any objections to merging this? The previous iteration from a few days ago was tested and is in PX4. In PX4/PX4-Autopilot#26307 it is used as and input to correct the dead reckoning estimate from known position on GCS in https://youtu.be/CMGQJNPiTJg?si=NVTHzn5PdF6h4tq0&t=1069

It is also streamed to a GCS. The message was slighlty different then, but the fundamentals of their use case were tested. I doubt they have tested every possible input source but I don't think they need to.

There is a PR to take the current version in PX4/PX4-Autopilot#26307
Note, PaulR also wants it.

If we're not happy to merge, then we need to clarify the testing regime requried.

[julianoes]

No opinion but I'm not standing in the way.

[MaEtUgR]

Thanks for addressing this in the coordination call 👍

[hamishwillee]

Thanks for attending @haumarco and @MaEtUgR .

This was approved in https://github.com/mavlink/mavlink/wiki/20260225-Dev-Meeting