The data-mover service requires direct access to the ceph cluster
in order to snapshot volumes etc.
Add support for the ceph-client interface; configuration and keyring
are writen to a charm specific location to avoid interference with
any other ceph services that may be deployed in the same unit.
TrilioVault requires some slight specialised ceph keyring and conf
placement - see code for notes.
Ensure that the charm uses the default release selector from
charms.openstack. This will ensure that the charm correctly
detects the OpenStack release and switches between Python 2
and Python 3 TrilioVault packages correctly.
Changing the triliovault-pkg-source configuration option will
be used as a trigger to update apt sources and upgrade any
required packages from the new repository.
Also adds initial support back to Queens automating the switch
between Python 2 and Python 3 at Rocky.