(CI request) Provide Linux AppImage in nightly builds

[hardBSDk]

The major cross-platform emulators offer AppImages for Linux, like RPCS3 and PCSX2.

There are any blocker for this?

[hd-genius]

The biggest hurdle right now is that currently Linux is failing to build due to several issues. I'm not familiar with the current CI pipeline, but I'll definitely check this out once I get the remaining Linux build issues resolved.

[Samueru-sama]

Hi, @lucasmz1 made an AppImage here but for some reason Xenia creates a bunch of cache dirs in the current working directory?

[RodoMa92]

Xenia-canary now has a proper compiling build now. I have integrated quite a lot of Linux stuff proposed here over the years and it just requires now a d3d12 back end implementation.