During TUI launch, turn systemd ShowStatus off. We don't want to do that
earlier, if we did then the easier path would be quiet boot or something
similar. This is done here so that service completion messages don't
overwrite the console.
* adjust environment to set PYTHONPATH to pick up site-packages
* add more required packages
* add script for subiquity-server, and set PYTHONPATH there,
so that the PYTHONPATH takes effect
* Abstract resource file lookup relative to SNAP
Using SNAP to find the resource files is a bit of an odd requirement for
non-subiquity clients. Start abstracting that away so it's easier to
change later.
Also move loadkeys to lookup from this, since the previous solution is
still a problem for ubuntu-desktop-installer.
* Move loadkeys / configure-apt to bin
loadkeys / configure-apt are in usr/bin only when we specially put them
there by way of snapcraft, which makes things a little harder on
non-subiquity clients. Move them to bin, which is to say don't have
snapcraft put them in usr/bin.