Include contributors and groups in the people watching bugs in bugzilla
Basically we were only including the POC and people who set their watch
access correctly, but contributors are supposed to be looking at issues
by default, they can then opt-out using 'unwatch'.
Groups were simply entirely ignored while they are present also in the
list of watchers.
Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>