WIP: Setup `postgres-from-snapshot` module to update the gstg DB
We create a new
generic-stor-from-snapshot module, which is a striped down version of
(it doesn't create a new subnetwork or firewall, it expects to use those created by another module)
that allows us to provision a machine from a snapshot.
We use this to add the module
postgres-from-snapshot on gstg, which also applies a pseudonymization script
to the data.