[infrastructure] [macos] use QGIS-Mac-Packager dependencies to setup MacOS CI build with GitHub workflows. Use CMake's define QGIS_MAC_DEPS_DIR to define folder to dependencies
* pyqtwrappers update (add QtNetwork, QtXml, QtSql, QtTest, uic)
* 2to3 updates
* move QPyNullVariant/NULL to PyQt.QtCore
* add global unicode/basestring/long for Python3
* expand QtGui, QtCore module and star exports
* Qscintilla2
* replace Set import with set builtin