ci: add wayland support to AppImage releases

[danielfrrrr]

Currently, when you run melonDS with QT_QPA_PLATFORM=wayland ./melonDS-x86_64.AppImage, you get this error:

qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: xcb.

This is because linuxdeploy-plugin-qt needs to explicitly configure wayland support at build time. That is what this PR does.

Reason for adding the new dependency:

$EXTRA_PLATFORM_PLUGINS needs the files /usr/lib/{aarch64,x86_64}-linux-gnu/qt6/plugins/platforms/{libqwayland-egl.so,libqwayland-generic.so}, found in the qt6-wayland package.

References for my implementation:
https://github.com/linuxdeploy/linuxdeploy-plugin-qt#environment-variables
PCSX2

With this PR, this issue will eventually be closed: #2386. In Qt 6.9, support was added for wayland clients to set their window icon using setWindowIcon, which in turn uses the wayland xdg-toplevel-icon protocol. However, AppImage is currently being built and packaged against a version lower than 6.9, due to the fact that the Ubuntu image of the GitHub Actions runner is using version 24.04 LTS, where the qt6-wayland package is still at version 6.4! Therefore, this PR is the first step, then it is just a matter of waiting for GitHub Actions to update its system to a version that has Qt 6.9, and the icon will likely be available in wayland.

[Arisotura]

gonna see if this builds fine - if so, I'll merge it