Installation issues with a couple examples

There are installation issues for examples in a couple modules:

# ls /usr/lib64/qt6/examples/**/lib64
/usr/lib64/qt6/examples/grpc/clientguide/lib64:
qt6
/usr/lib64/qt6/examples/multimedia/video/qmlvideo/lib64:
qt6
/usr/lib64/qt6/examples/quickcontrols/attachedstyleproperties/lib64:
libMyStyle.so
/usr/lib64/qt6/examples/quick/imageprovider/lib64:
libqmlimageproviderplugin.so
/usr/lib64/qt6/examples/quick/imageresponseprovider/lib64:
libqmlimageresponseproviderplugin.so

• For qtmultimedia: `INSTALL_EXAMPLEDIR` is redefined in examples/multimedia/video/qmlvideo/frequencymonitor, examples/multimedia/video/qmlvideo/qmlvideo and (in 6.8) examples/multimedia/video/qmlvideo/performancemonitor
• For qtdeclarative examples, the way libMyStyle.so, libqmlimageproviderplugin.so and libqmlimageresponseproviderplugin.so are installed break examples if QT_DISABLE_RPATH is enabled. Makes me wonder if these libraries really have to be shared and installed.
• qtgrpc is apparently already fixed, clientguide_server location is correct in 6.9.0 RC