libtracker-common: Moved tracker-ontologies.h into libtracker-sparql

The Namespace has been cleaned up too, all APIs now start with:

  TRACKER_PREFIX_

or

  TRACKER_DATASOURCE_

The well known definition for the TrackerMinerFS graph has also been changed
to:

  TRACKER_OWN_GRAPH_URN

because it now applies to more than just the TrackerMinerFS, we're using it
in:

  tracker-writeback
  tracker-miner-apps
  tracker-miner-user-guides
  ...
  libtracker-data

It should probably be internal actually.