False positive type check error for VisibilityKind

[bergmanngabor]

The following piece of VQL code compiles:

    privateLiteral ==  VisibilityKind::^private;
    Property.visibility(attr, privateLiteral);

The following, however, does not:

    Property.visibility(attr, VisibilityKind::^private);

In particular, a type check error is raised: "Invalid enumeration constant VisibilityKind".

Speculation: This might be related to the quirk that NamedElement::visibility is typed by the EDataType NamedElementVisibility; while VisibilityKind is merely the implementation class of the latter. Maybe this is what confuses the type checker (in which case it may be a Viatra issue that should be solved in general, not just for V4MD).