[Development] Remaining tools in CMAKE_INSTALL_BINDIR

[Ulf Hermann]

>> My question was for the developer's own plugins. Are these tools meant for
>> the developer to test their QML importing their plugins? It might be
>> surprising that it cannot find the plugins they've just installed to
>> QML_PLUGIN_PATH, or worse, finds an older version of them.

Indeed if you actually have both Qt5 and Qt6 available, a single qml or 
qmlscene executable cannot cover them both. So, let's make them versioned.

best regards,
Ulf