Add AppImage CI build

[lambdcalculus]

What it says on the tin.

Requires #1003 so that paths in the AppImage are resolved correctly.

[TrickyLeifa]

The CI needs changed to be built against Ubuntu 22.04 rather than the latest as to ensure compatibility.

[Salanto]

After messing around I found two minor things :
The AppImage does not have an application icon and that its missing the execution bit on Linux, so people need to either chmod it or use the file property dialog. I think just adding the bit to the appimage before zipping should be enough to make it portable.
Otherwise works on anything never than 22.04 LTS (without updates) since it links to a GLibC that is not present on 20.04 LTS

[lambdcalculus]

Apparently the artifact clears the executable bit? This also seems to be happening to the dynamic build. Neither launch.sh nor the executable really come in as with x bit set, despite them being set in the CI.

[stonedDiscord]

The CI latest image has burnt us before with Mac
Can you be more specific about the version

[lambdcalculus]

I already set the Linux CI to ubuntu-22.04. I kept the formatting check on ubuntu-latest, since it doesn't really matter, so that might be what you saw.

[Salanto]

Any final objections here? @stonedDiscord @TrickyLeifa

[stonedDiscord]

Does the appimage work?

[lambdcalculus]

Works fine on my end. There are still some aspects that I can work out later, though, like how it doesn't seem to have an icon, or how appimagetool complains about a lack of update information when making the AppImage. But this is good for a start I think.

[Salanto]

Tested and the executable bit is set properly.

[lambdcalculus]

The AppImage does not have an application icon

Ah, I should say, icons only work if you have appimaged and configure it appropriately, I believe.

I think most desktop environments have a default icon for AppImages though. At least KDE does, from when I used it.

[stonedDiscord]

Apparently the artifact clears the executable bit? This also seems to be happening to the dynamic build. Neither launch.sh nor the executable really come in as with x bit set, despite them being set in the CI.

zip files don't support the executable bit, you'd have to put it in a tar file before to keep the bit.