Added testing for std::optional functionality of Gaudi::NamedRange
This follows from the implementation of std::optional<Gaudi::NamedRange> in !1624 (merged) and resolves issue #340 (closed). It adds OptionalSRangesMerger which takes a list of Gaudi::Range TES locations, which it then loops over, checks the optional and prints the size if it has a value.
Edited by Daniel Magdalinski