The original workaround was only supposed to apply to QList/
QVector of QVariantMaps. By replacing them all in sip we
break mapping of signals defined in c++ which are emitted
by Python code.
Fixes exceptions after running processing algorithms in Qt6
builds.
The old sip based approach to handling property -> getter/setter
conversion is broken on sip6, so move the patching into Python.
Also fix incorrect checks in tests, and add additional test
for compatiblity code.
And make sipify handle this nicely. This means that all our non-flag
style enums correctly map across to IntFlag python enums on Qt 6,
fixing issues with negative enum values for these and providing
a better match for the original c++ enum.
