Flight Data status screen should show values for 2nd compass

In the Status screen we can see magfield, mx, my, mz which shows the primary compass's values. It would be useful to be able to see the secondary compass's values as well.

The underlying motivation is to allow users to determine if they have two working compasses or not. There may be other places that would be more intuitive like printing "MAG:2" under the "AS" and "GS" field on the flight data screen. Basically as long as there's some way to see that two are operating that'd be great.

Start by locating the Flight Data Status screen and the existing magfield, mx, my, and mz values. Check how the primary compass values are displayed, then determine whether the secondary compass should appear there or near the AS and GS fields. Done means users can clearly tell whether two compasses are operating.

Written by the indexing model from the issue text.