[Development] Remaining tools in CMAKE_INSTALL_BINDIR

[Ulf Hermann]

>> I would consider qml, qmlscene, qmlpreview, qmlprofiler, and qmltime to
>> be equivalent to their Qt 5 versions, and indeed user-facing.
> 
> And would replacing the Qt 5 versions with Qt 6 be an imperceptible change to
> the user? What happens if their own QML content has plugins? I assume Qt
> itself ships equivalent plugins to everything that hadn't been deprecated
> before 6.0.

In a parallel install the Qt5 and Qt6 QML import paths should be 
separate. If you ship your own QML modules you can in principle build 
them against both Qt5 and Qt6, separately, and install them in the 
respective import paths. But I don't know if anyone actually does that.

We made an effort to keep Qt's own QML modules source compatible between 
Qt5 and Qt6, including versions. However, there are modules that 
blatantly break compatibility. QtMultimedia and QtLocation come to mind. 
No idea if those were deprecated before they were re-created for Qt6.

>> qmlplugindump is the same as in Qt5. It should be a build tool, but it
>> is not, due to ... shortcomings. People generally invoke it manually.
>> Also, it's deprecated in Qt6.
> 
> Can we disable its build & installation by default?

I guess that would make some people rather unhappy. I've seen some cold, 
dead hands clutching qmlplugindump.

Also, qmlplugindump actually loads plugins. So, although it's almost the 
same source code you cannot use the Qt5 qmlplugindump to read Qt6 
plugins, or vice versa.