Package as flatpak or appimage

<!-- DO NOT POST LINKS OR REFERENCES TO COPYRIGHTED CONTENT IN YOUR ISSUE. --> **What version of this package are you using?** N/A **What problem do you want to solve?** I don't want to rely on distro specific packages yet still want to use mpv-webtorrent-hook (mpv has an appimage) **What do you think is the correct solution to this problem?** Package webtorrent-cli as an appimage or as a flatpak (or maybe submit a portable binary to the AM database) **Are you willing to submit a pull request to implement this change?** No (I'm down to help tho)