fix(fmgc): multiple FMGC fixes and small additions

[lukecologne]

Fixes #9661

Summary of Changes

This PR adds some small fixes for the FMGC mode logic:

• Use correct bits for the EXP CLB/DES mode sync, and add EXP bits to the CLB/DES mode sync. This prevents incorrect mode switching or reversions when changing the master FMGC (i.e. AP switching, or FMGC failure) while EXP CLB/DES is engaged.
• Reset all engaged modes at engine start, to ensure a consistent configuration for takeoff if any modes were engaged when the engines were not yet started.
• Fix triple click sounding when entering global speed protection (FD auto deactivation), even when no FD was engaged
• CAT 1 capability is now shown instead of CAT 2 when no RA indicates NO
• Re-add support for the A32NX_FG_RNAV_APP_SELECTED LVar
• Fix missing abs() in the NAV capture condition, to prevent immediate NAV activation when having a negative XTK, regardless of the actual distance to the path
• Raise default RA value (when both RAs are FW) to 2500ft, to enable LOC arming when all RAs are failed

Screenshots (if necessary)

References

Additional context

Discord username (if different from GitHub):

Testing instructions

• Check that the fixes listed above work as described (where applicable, i.e. excluding the A32NX_FG_RNAV_APP_SELECTED Lvar)
• Check that the FG in general works as expected (not a full flight needed, a takeoff/departure and approach should be enough)

How to download the PR for QA

Every new commit to this PR will cause new A32NX and A380X artifacts to be created, built, and uploaded.

1. Make sure you are signed in to GitHub
2. Click on the Checks tab on the PR
3. On the left side, find and click on the PR Build tab
4. Click on either flybywire-aircraft-a320-neo, flybywire-aircraft-a380-842 (4K) or flybywire-aircraft-a380-842 (8K) download link at the bottom of the page

[lukecologne]

Converting to draft as there as some more changes I want to bring in

[tracernz]

It would be better to summarise what the fixes are in the title if possible as this is the one we will see when it’s squash merged. fix is already the first word so that’s redundant.

[lukecologne]

It's a bit hard, since they're basically all independent fixes

[tracernz]

Dev Team QA report

Discord Username : tracernz
Object of testing : #9652
Aircraft : A32NX
Tier of Testing : 2
Date : 07/02/2025
Testing Process:
Performed a full flight, while testing along the way.

• Tried EXP CLB, changing APs while in process.
• Tried capturing NAV from both sides with XTK > 5 NM.
• Turn off FDs and enter speed protection.
• Tried EXP DES, changing APs while in process.
• Fail both RAs on approach and check for CAT I, and ability to arm LOC.

Testing Results:
Passed