[Backport] Add "enum class" values to the enum type in Python

Enum class values seem to have pretty generic names (as there is no danger
of name clashes in C++, as they must always be prefixed with the enum
class name). So add them to the enum type in Python too, so one can
always write something like QActionGroup.ExclusionPolicy.None instead of
QActionGroup.None.

Ideally we wouldn't add the enum values to the parent class at all, but
I don't want to break compatibility with older versions of PythonQt.

(cherry picked from commit MeVisLab/pythonqt@c35d010)

Author: usiems

src/PythonQtClassInfo.cpp

@@ -853,12 +853,26 @@ PyObject* PythonQtClassInfo::findEnumWrapper(const QByteArray& name, PythonQtCla
   }
 }
 
+// required for the code below (for versions before Qt 6)
+Q_DECLARE_METATYPE(PythonQtObjectPtr)
+
 void PythonQtClassInfo::createEnumWrappers(const QMetaObject* meta)
 {
   for (int i = meta->enumeratorOffset();i<meta->enumeratorCount();i++) {
     QMetaEnum e = meta->enumerator(i);
     PythonQtObjectPtr p;
     p.setNewRef(PythonQtPrivate::createNewPythonQtEnumWrapper(e.name(), _pythonQtClassWrapper));
+#if QT_VERSION > 0x050800
+    if (e.isScoped()) {
+      // add enum values to the enum type itself, in case enum value names are so generic
+      // that they are not unique
+      for (int j = 0; j < e.keyCount(); j++) {
+        PythonQtObjectPtr enumValuePtr;
+        enumValuePtr.setNewRef(PythonQtPrivate::createEnumValueInstance(p.object(), e.value(j)));
+        p.addVariable(e.key(j), QVariant::fromValue(enumValuePtr));
+      }
+    }
+#endif
     _enumWrappers.append(p);
   }
 }