Use distro-specific icons from Lukewh/quickemu-icons for shortcuts

[daPhipz]

@Lukewh provides distro-specific icons for quickemu in their repo. I think it would be nice if we would use them for shortcuts created by quickemu --shortcut, instead of just the quickemu icon.

[Lukewh]

If this is going to happen, I think there are at least three options:

1. quickemu pulls down the latest release and extracts the appropriate icon (a lot of effort for quickemu with extra downloads etc. that seem out of scope for quickemu)
2. the quickemu-icons repo exposes the icons at consistent URLs that quickemu can download on demand when the --shortcut argument is passed
3. quickemu includes all the latest icons in its release