timing: Have the segment store view use lazy iterables

timing: Have the segment store view use lazy iterables

Views will make lazy-load the data using an iterator instead of a
collection of segments. This will avoid having to have all segments in
memory.

Change-Id: I9cb9f2f9db621cb9789537882ab95b8ba239e59a
Signed-off-by: Geneviève Bastien <gbastien+lttng@versatic.net>
Reviewed-on: https://git.eclipse.org/r/83724
Reviewed-by: Hudson CI