Include an AppImage release

[ProjectSynchro]

This would allow for cross-distribution "packages" that work anywhere.
And seeing as it appears that electron-builder is being used here, it should support creating appimages without much (if at all any) work.

Personally, I use Flatpak for a select few applications that require a 'sandbox' environment and stick to appimages where I can.
It would be awesome if an AppImage could be used here as well :) (This is the only snap I actually use, and snapd is a PITA to keep working on Fedora for some reason.)

[FelicianoTech]

I will consider this.

A quick minute of research though suggests that I can't use electron-builder to build n AppImage with desktop integration. So I'll have to use an additional tool (which isn't out of the question).

I would love for others who would want an AppImage of this project to +1 the first post.