This implements our planned short (medium...?)-term hack of
having test systems forward test priority information to RDB,
in the absence of any other way for consumers (e.g. releng) to
know which tests they really have to care about for any given
workflow.
The concept here is that we specify the relevant workflow in
the key name ('priority.fedora.compose') and the values are
expected to be integers, with *lower* values meaning 'more
important' and *higher* values meaning 'less important'. For
this workflow, 1 means 'critical system functionality' (i.e.
the most important kind of test), 2 means 'Alpha priority',
3 means 'Beta priority', 4 means 'Final priority', and anything
5 or higher is Optional.
Signed-off-by: Adam Williamson <awilliam@redhat.com>