ss: introduce getIteratorOverQuark

ss: introduce getIteratorOverQuark

This patch adds a method which returns an iterator over the
intervals of an attribute and a basic unit test.

Change-Id: I8d9d59b1cdf1a80477f24e2849c777c109afbc10
Signed-off-by: Loïc Prieur-Drevon <loic.prieurdrevon@gmail.com>
Reviewed-on: https://git.eclipse.org/r/77546
Reviewed-by: Alexandre Montplaisir <alexmonthy@efficios.com>
Tested-by: Alexandre Montplaisir <alexmonthy@efficios.com>
Reviewed-by: Genevieve Bastien <gbastien+lttng@versatic.net>
Reviewed-by: Hudson CI