nixos/gnome: enable MTP support in gvfs

To support browsing files on Android phones in Nautilus (and other GVFS
based file browsers).
nixos/mesos: fix typo
Merge pull request #5299 from bjornfor/gnome-enable-mtp-support

nixos/gnome: enable MTP support in gvfs
Merge pull request #5300 from ambrop72/virtualbox-network-interface

virtualbox: Allow disabling the network interface.
Add cava, console-based Audio Visualizer for Alsa
virtualbox: Unbreak the nixos module.