This is in line with QMetaType and will be used to implement a mutable
QSequentialIterable. Later on, a QMetaAssociation will be added as
well, to implement a mutable QAssociativeIterable.
The code here represents the minimal set of functionality needed to have
a practical sequential container. The functionality is not completely
orthogonal. In particular, the index based operations could be
implemented in terms of iterator-based operations.
Task-number: QTBUG-81716
Change-Id: Ibd41eb7db248a774673c701549d9a03cbf2e48b6
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
