timing: Add statistics for time events in the flame graph view

timing: Add statistics for time events in the flame graph view

This will show users the statistics for each aggregated function in the
flame graph view.

The statistics are shown in the tooltip of each time event ( aggregated
function).

This shows the maximum/minimum duration,maximum/minimum self time,number
of calls, deviation and the average duration of each function.

Change-Id: I0d4c2f4da12a334d76d5173f68397f5f1e7abadf
Signed-off-by: Sonia Farrah <sonia.farrah@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/78500
Reviewed-by: Genevieve Bastien <gbastien+lttng@versatic.net>
Tested-by: Genevieve Bastien <gbastien+lttng@versatic.net>
Reviewed-by: Hudson CI
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>