fix(a380x): Consider .flt file loading state for WASM startup

[flogross89]

Summary of Changes

Changes the startup and initialization phase for A32NX and A380X, which hopefully solves some problems for MSFS2024.
Now, A32NX_IS_READY is only set when the FLT file has been fully loaded.

Screenshots (if necessary)

References

Additional context

Discord username (if different from GitHub):

Testing instructions

MSFS2020 and MSFS2024: Load aircraft in different scenarios (apron, runway, in flight) and verify that the plane spawns as expected.

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

[tracernz]

I think it's a bit dangerous to ignore SimConnect messages like that, and will lead to confusing bugs. Loading .flt files will not work correctly for instance if we've intercepted/blocked a key event that's used to load the .flt file, and then ignored the event message.

[flogross89]

I think it's a bit dangerous to ignore SimConnect messages like that, and will lead to confusing bugs. Loading .flt files will not work correctly for instance if we've intercepted/blocked a key event that's used to load the .flt file, and then ignored the event message.

Which change is this comment referring to?