bug: camera manager not presenting cameras correctly over MAVLink

[ES-Alexander]

Bug description

QGroundControl allows switching between the camera streams it receives information about via MAVLink, but there seems to have been a regression in the camera manager that no longer supports that functionality.

Steps to reproduce

1. Install BlueOS-1.1.1 on a system with multiple video streams
2. Open QGroundControl
3. Set a joystick button function to "Next Camera" or "Previous Camera"
4. Pressing the button while in Fly View switches the camera feed, as expected
   • From the release notes, this seems to use MCM t3.12.1 ✅
5. Install BlueOS-1.2.0-beta.1 (or any more recent version)
6. Joystick switching no longer works
   • MCM >= t3.12.4 ❌

Primary pain point(s)

Users can't switch camera streams in QGC (and other applications/programs using the same mechanism), which wastes their additional camera hardware and bandwidth usage.

Additional context

First raised in this forum thread.

Prerequisites

• [X] I have checked to make sure that a similar request has not already been filed or fixed.