Qt 6.2 introduced an issue where SingleSelection item views would
deselect the current item if the user clicked on empty area in the
widget.
This was very confusing in the scene tree as it was now possible to
unselect the current scene. A workaround for this in OBS was added in
08e4ee6 and expanded on in dc30cf0, but being quite hacky it never was
the perfect solution.
I since dug into Qt and fixed the issue upstream in qt/qtbase@f11e5435c7
for Qt 6.4.3 and newer, so we can remove the workaround when using those
versions (with the long term goal of removing the code altogether).
In the scene tree, we currently prevent deselecting items by
automatically reselecting a new one to workaround a regression in Qt 6.2
that would let users unselect items even in SingleSelection QItemViews.
When clearing however, we explicitly want to unselect the currently
selected item, so we should avoid reselecting it in the SceneTree.
