tmf: Bug 428432: A trace moved to an experiment loses its trace type

tmf: Bug 428432: A trace moved to an experiment loses its trace type

- Updated all setting of trace persistent properties to use the common
method in TmfTraceTypeUIUtils, which refreshes the trace type.

- Updated the method to accept the resource as argument and to be able
to set the trace type of a trace element under an experiment.

- Added getExperiments() method to TmfExperimentFolder, and cleaned up
some code to use it.

Change-Id: I3446ac77d9929c7688a4b92fe8094b9428f15524
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/22337
Tested-by: Hudson CI
Reviewed-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
IP-Clean: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Tested-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
IP-Clean: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>