[Feature request] .zip (and maybe .7z) support

[kenderipa]

Hello,

could you please add .zip and .7z support? If the project isn't abandoned, that is.

Context: some AppImages are zipped, and in this case zap throws an exception and dies.

[srevinsaju]

Looks like a valid use case, I will put in a good first issue tag for new contributors. Meanwhile, could you post some examples of appimages that are zipped?

[kenderipa]

Sure.

https://github.com/citra-emu/citra-nightly/releases/tag/nightly-2011
https://github.com/scp-fs2open/fs2open.github.com/releases/tag/release_23_2_0 (Linux tarball contains two AppImages)
https://github.com/HarbourMasters/Shipwright/releases (those Linux .zips each contain an AppImage)

[HugKitten]

https://github.com/DevilXD/TwitchDropsMiner/releases/tag/dev-build