Motivation for this change

vifm includes some optional features what are currently no-op due
to missing dependencies. Once such example is vifm-media.

vimfm-media is a Linux script included with vifm which can be used to
mount/umount removable media from within vifm. However, vifm-media
has additional dependencies, namely Python, dbus, and a supported
back-end such as udisks2. While vimfm-media is currently installed,
it fails with the error "No supported backend found."

This change adds optional support for vifm-media via the new package
vifm-full; Opening for the opportunity to add whatever optional
dependencies I have not considered in this change in the future,
while not generously increasing the closure size of the original
vifm package.

For reference, vifm has a closure size of 41,164,432 while the new
vifm-full increases this to 382,642,536. Calculated with
nix path-info -S

Note: While vifm-media supports numerous back-ends, this change only
adds support for udisks2. In addition, vifm-media is not supported on
MacOS/OSX, for which upstream provides an alternative script.

Using media support in vifm-full

With vifm-full, when you use the :media command you're presented with a list of mountable and mounted removable media devices (ex. USB flash drive). Select one with ENTER to mount it (if needed) and navigate to the mount point. To unmount, use the :media command but press the "m" key instead of ENTER.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @ raskin