fix(a380x/vd): Bug fixes and additions

[Jonny23787]

Fixes #[issue_no]

Summary of Changes

• Add VIEW ALONG ACFT TRK message
• Add flight path angle arrow
• Add ALT SEL message
• Add NOT VALID PITCH ATTITUDE symbol and ATT message
• Improve ALT CST logic

Screenshots (if necessary)

References

Additional context

Discord username (if different from GitHub):
jonny_23

Testing instructions

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.

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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