tmf: Support folders in tracing projects

tmf: Support folders in tracing projects

- Modify TmfTraceFolder to allow child TmfTraceFolder

- Create TmfTracesFolder sub-class for the unique traces folder

- Add ITmfTrace.initTrace() signature to support trace name

- Use element path for trace name

- Add New Folder command that applies to all trace folders

- Support Rename and Delete command on trace folders

- Update Rename Trace and Delete Trace commands to support traces under
trace folders

- Move Rename Trace workspace handling from dialog to handler class

- Update Select Traces command and its dialog to support traces under
trace folders

- Update Events editor initialization to support traces under trace
folders

- Update editor link helper to support traces under trace folders

- Refactor getProject() method on project model elements

- Update navigator label provider to show element path for traces under
experiments

- Create TmfViewerSorter to prioritize folders over traces and traces
over analyses

- Change Select Supplementary Files dialog to show element path

- Change supplementary folder handling to support traces under trace
folders and to create folders only if necessary

Change-Id: I3b68bb389b5e0b0bf894eb34affada98b117fb31
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/25324
Tested-by: Hudson CI
Reviewed-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Tested-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>