tmf: Fix and simplify State System Explorer viewer

tmf: Fix and simplify State System Explorer viewer

- Simplify code and reduce the number of private methods
- Wait for initialization of state systems
- Make the viewer always detect new attributes on update
- Indicate refresh needed on visible range update only if new attributes
found
- Keep root, trace and state system entries on update in filter mode
- Avoid recomputing list of traces, analysis modules and state systems
at every update
- Highlight changed attributes in filter mode
- Implement toString() for tree viewer entries
- Expand tree to auto-expand level after refresh to show changed items
in filter mode

Change-Id: I4c7b9c6c6313733ee94ae9b4e800f78fe085ff64
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/30538
Tested-by: Hudson CI
Reviewed-by: Bernd Hufmann <bernd.hufmann@ericsson.com>
Tested-by: Bernd Hufmann <bernd.hufmann@ericsson.com>