TMF: Synchronize an experiment instead of collection of traces

TMF: Synchronize an experiment instead of collection of traces

That will make it compatible with streaming since one full trace does not
have to be read before the others. It will also accelerate the time necessary
to get results, as matches will be found earlier. The overhead of reading the
experiment instead of the traces decreases performance though.

Change-Id: I7c94c21e63781b2cae0faead915be8959170a992
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/35350
Tested-by: Hudson CI
Reviewed-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>