Use fallback-x11 instead of x11 socket in Flatpak to improve safety label

[poly2it]

As I understand it, TurboWarp is currently assigned a more dramatic safety label than necessary because it is set to use x11 windowing by default. Importantly, resolving this issue would change the rating in GNOME Software from Unsafe to Potentially Unsafe. For the GCompris Flatpak, this was resolved by simply changing socket x11 to fallback-x11 in the packaging configuration (see issue). Would this be possible for the TurboWarp Flatpak as well, or would it require further work on the program?

[GarboMuffin]

pretty sure we're still gonna have a very scary warning because we need --device=all to access webcams for video sensing but yeah we can try that

[GarboMuffin]

To use --socket=wayland and --socket=fallback-x11 the app needs to default to Wayland and then fallback to X11. Electron still defaults to X11; I interpret that as a sign that Wayland support is not mature enough to enable by default.

I'll try to make it so that if you manually add --socket=wayland using Flatseal, we'll actually use Wayland now that it doesn't immediately segfault. This would match what other Electron flatpaks do: https://github.com/search?q=org%3Aflathub%20ozone-platform-hint&type=code

[GarboMuffin]

Once the latest push goes up, if you use Flatseal to manually add --socket=wayland, it will use wayland and you can remove x11 if you want

From playing around in a VM I can tell that it's still not ready for primetime