Publish binaries on release

[michaelbeaumont]

For any non-Fedora/non-Debian it'd be great to just have these binaries available. I'd love to build & maintain an Arch AUR for credentialsd/xdg-desktop-portal

[iinuwa]

We try to dynamically link libraries as much as possible, so this might not work across distros very smoothly. I think as a starting point, we could add a section to the BUILDING.md for building and installing via Arch. Then maybe we can turn that into a credentialsd-git package in AUR that builds the package locally? Then we can figure out if a credentialsd-bin is feasible.

I think given all the recent attacks on AUR, I think it would make most sense to host the PKGBUILD(s) in this repo to give it further trust. If you'd like to create a PR for that, then feel free to put it in distrib/arch/PKGBUILD