extract method to determine whether a "server" pathname represents a directory of schema files

Change-Id: Ib850295b8a2c8216ef7cb1240e92f9ab10c7f4ca
Improve functionality of UR_TEST_FILLDB with table inheritance

Previous code wouldn't handle classes that inherit from other classes,
where each class has a table.

Change-Id: I1f247873ceb9ff0c0595e9480b9cad3ca39ff640