tmf: Add trace entry parent in Call Stack view

tmf: Add trace entry parent in Call Stack view

The root entries in the Call Stack view tree are now trace entries and
the thread entries are child of their corresponding trace.

The CallStackEntry and ThreadEntry classes now extend TimeGraphEntry.

The thread name is now displayed in the tool tip.

Change-Id: I91091d492d3304ad1cd5588af807e18c65093e8f
Signed-off-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-on: https://git.eclipse.org/r/29835
Tested-by: Hudson CI
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>