Add missing prereqs for `firefox` wrapper

- `x-is-active` tests that `Xvfb` started up properly
- `x11vnc` to view the running `Xvfb`
- `myod` generally useful "my" "od" (octal dump)
Take ownership of `/mnt` directory
Add OpenConnect (VPN tool)
Add user to audio and Wireshark groups
Install Mosh on everything