Fixed race issues in config upload, tested to be reliable now - board startup scripts now need the other half of testing

Instantiate a PX4 config view in PX4 mode from start, since boards with just the bootloader (or no working telemetry) cannot be flashed else.

Checkpoint: RC calibration much better / operation, can use UI tweaks. Airframe config in, but not operational and still very functional / ugly.

Implementation of Battery Monitor configuration, and addition of AP2ConfigWidget, which automatically handles UAS connections to allow for simpler configuration window code.

Fixed styling of the toolbar, specifically coloring and sizing of the buttons, and made the labels aware of the current window theme. Also made some changes to updating the toolbar when switching UASes or when UASes disconnect/reconnect.

The QGCUnconnectedInfoWidget now remains square and has more rounded edges so that it looks more like a button.

Removed OpenGL dependency in HUD, merged in HUD from Soren Kuula and config changes from Michael Carpenter

The light and dark themes now use slightly different blues for their accent colors that is higher contrast.

The background color of the mission items is now controlled by stylesheets as well. This change also fixed restyling the mission lists when a style change occurred.