QmlProfiler: Methods for dispatching events by feature

When announcing features models have to provide functions that handle
events for those features now. The model manager gets a function to
dispatch events to the models that subscribe to them.

Change-Id: I3fd80443a68ba264a513d8d53ed473cf072f1dc7
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>