Qt3D*/QtDataVis nested modules

I'm trying to use Qt3D and QtDataVisualization components.

The modules can be imported but the Qt3D* and QtDataVisualization do not provide symbols directly, but under a submodule with the same name, eg PySide2.Qt3DCore.Qt3DCore so if I want to use QArmature I have to specify  Qt3DCore.Qt3DCore.QArmature:

```

$ python3 -c "import PySide2; print(PySide2._version_)"

5.12.3

$ python3 -c "from PySide2 import QtCore, Qt3DCore"

$ python3 -c "import sys, inspect; from PySide2 import QtCore; print(inspect.getmembers(QtCore, inspect.isclass))"

[('ClassInfo', <class 'PySide2.QtCore.ClassInfo'>), ('MetaFunction', <class 'PySide.MetaFunction'>), ('Property', <class 'PySide2.QtCore.Property'>), ('QAbstractAnimation',...

$ python3 -c "import sys, inspect; from PySide2 import Qt3DCore; print(inspect.getmembers(Qt3DCore, inspect.isclass))"

[('Qt3DCore', <class 'PySide2.Qt3DCore.Qt3DCore'>)]

$ python3 -c "import sys, inspect; from PySide2 import Qt3DCore; print(inspect.getmembers(Qt3DCore.Qt3DCore, inspect.isclass))"

[('ChangeFlag', <class 'PySide2.Qt3DCore.Qt3DCore.ChangeFlag'>), ('ChangeFlags', <class 'PySide2.Qt3DCore.Qt3DCore.ChangeFlags'>), ('QAbstractAspect', <class 'PySide2.Qt3DCore.Qt3DCore.QAbstractAspect'>), ('QAbstractSkeleton', <class 'PySide2.Qt3DCore.Qt3DCore.QAbstractSkeleton'>), ('QArmature', <class 'PySide2.Qt3DCore.Qt3DCore.QArmature'>), ('QAspectEngine'

```

In pyqt this is fine:
$ python3 -c "import sys, inspect; from PyQt5 import Qt3DCore; print(inspect.getmembers(Qt3DCore, inspect.isclass))"
[('ChangeFlag', <class 'PyQt5.Qt3DCore.ChangeFlag'>), ('ChangeFlags', <class 'PyQt5.Qt3DCore.ChangeFlags'>), ('QAbstractAspect', <class 'PyQt5.Qt3DCore.QAbstractAspect'>), ('QAbstractSkeleton', <class 'PyQt5.Qt3DCore.QAbstractSkeleton'>), ('QArmature', <class 'PyQt5.Qt3DCore.QArmature'>), ('QAspectEngine', <class 'PyQt5.Qt3DCore.QAspectEngine'>), ('QBackendNode', <class 'PyQt5.Qt3DCore.QBackendNode'>), ('QBackendNodeMapper', <class 'PyQt5.Qt3DCore.QBackendNodeMapper'>), ('QComponent', <class 'PyQt5.Qt3DCore.QComponent'>), ('QComponentAddedChange', <class 'PyQt5.Qt3DCore.QComponentAddedChange'>), ('QComponentRemovedChange', <class 'PyQt5.Qt3DCore.QComponentRemovedChange'>), ('QDynamicPropertyUpdatedChange