tmf: Support dynamic marker event sources

tmf: Support dynamic marker event sources

The signal TmfMarkerEventSourceUpdatedSignal is added to notify
components that a marker event source has changed and that markers and
marker categories need to be refreshed.

The zoom threads in abstract time graph views are changed to update the
marker categories along with the marker lists, to ensure they match.

Change-Id: I2c6fb2443a474d01d9d37ae5b6b8fc13a1ee7457
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/77415
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-by: Hudson CI
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>