Enable Controls to pass its import version to Templates

We need an "internal import" directive in qmldir that imports the specified module into the implicit import of all its QML files, does not re-export its types. At least that's the current idea. If not feasible some other solution has to be found.

With such a thing, we could add "internal import QtQuick.Templates/auto" to each of the styles' qmldir files and in turn drop the imports from the individual .qml files. This way templates would be imported with the same version as Controls.