reports wether the given type from this module of the given table is public should only be called from the global scope and with the SymbolTable that was in use when the type was declared.

holds state to check if the types of an AST are valid even though it is a visitor, it should not be used seperately from the parser all it's VisitX return values are dummy returns TODO: add a snychronize method like in the parser to prevent unnessecary errors.