Add unit test that checks Format data

Summary:
This unit test loads just one definition including its included defintions.
Then it gets all Formats of the definition + includedDefinitions(). In
theory, the format IDs now should be 1, 2, 3, ..., N.

What's currently not clear to me is whether this test is really correct.
I think so, but Jira.xml fails...

Test Plan: make && make test

Reviewers: cullmann, vkrause

Reviewed By: cullmann

Subscribers: kwrite-devel, kde-frameworks-devel

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D14978