Reorganization of DataValues extension's JS resources

- Moved dataValues.util.inherit into separate file.
- Test resource definitions cleanup (proper dependencies) and moved into separate file.
- DataValues Extension's QUnit tests are not longer dependent on MediaWiki (no longer using
  QUnit.newMwEnvironment).

Change-Id: I9ba230dba1c1df572b5d6eac952ea6043c2b2a8a