fosquitto: register to umdns via procd

This should enable foris-controller zeroconf machinery working even when umdns is used (it occupies port 5353) and makes it impossible for foris-controller to generete zconf announcements

After this patch the umdns will foris-controller compatible announcements.

Note that foris-forwarder needs to be bumped to process such announcements. But that has to be done after turris/foris-controller/foris-forwarder!1 (merged) is merged.