Fix X11 applications not starting in Wayland

[NetDwarf]

Remove --socket=fallback-x11 Remove X11 (on Wayland) specific workarounds in README

[flathubbot]

Started test build 108057

[flathubbot]

Build 108057 successful To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/90874/com.vscodium.codium.flatpakref

[noonsleeper]

@NetDwarf this is not compliant with flathub policies, that is why we change to wayland + fallback-x11

[NetDwarf]

@noonsleeper Thanks for making me aware!

According to https://docs.flathub.org/docs/for-app-authors/requirements/#unrestricted-permissions

--socket=x11 and --socket=fallback-x11 are mutually exclusive and either also need --share=ipc to be requested.

Having x11 and fallback-x11 (and wayland) is the current state.

In general there should not be --socket=x11 and --socket=wayland, beside a few exceptional cases.

Indeed the PR proposes an edge case, tho technically being compliant still. I'd say that the exception makes sense here since VSCodium is using X11 and Wayland for running compiled GUI applications in a native Wayland session. This does not make much sense for other applications that are either X11 or Wayland.

Of course, I can also revert and put the --nosocket=fallback-x11 in the README (I look up the actual switch then).

[flathubbot]

Started test build 121019

[flathubbot]

Build 121019 failed

[flathubbot]

Started test build 128884

[flathubbot]

Build 128884 successful To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/111871/com.vscodium.codium.flatpakref

[noonsleeper]

LGTM!