PyQt: Update to latest versions

PyQt5:
- devel/py-qt5-pyqt: Update to 5.15.11
- graphics/py-qt5-3d: Add port
- net/py-qt5-networkauth: Update to 5.15.6
- www/py-qt5-webengine: Update to 5.15.7
- x11-toolkits/py-qt5-chart: Update to 5.15.7
- x11-toolkits/py-qt5-datavis3d: Add port

PyQt6:
- devel/py-qt6-pyqt: Update to 6.7.1

Build tools:
- devel/sip: Update to 6.8.6
- devel/py-qt5-sip: Update to 12.15.0
- devel/py-qt6-sip: Update to 13.8.0
- devel/py-qtbuilder: Update to 1.16.4

The build tools are now all licensed BSD2CLAUSE and have been converted
to PEP517.