Model adapter/replica incompatible across different Qt versions and platforms

Model adapters/replicas doesn't work across different Qt versions / platforms, resulting in crashes due to unknown QVariant types and then failing to parse the data stream.

The issue is these types:

qRegisterMetaType<QtPrivate::ModelIndex>();
qRegisterMetaType<QtPrivate::IndexList>();
qRegisterMetaType<QtPrivate::DataEntries>();
qRegisterMetaType<QtPrivate::MetaAndDataEntries>();

Sometimes they get registered without the namespace (eg. "ModelIndex" instead of "QtPrivate::ModelIndex").

Currently on Qt 6.6.1 on Linux (gcc) they register without namespace, but on macOS (clang) they register with namespace.