tests: consider maintaining the test suite requirements as a submodule in the repository

[nagisa]

It looks like the test descriptions are expected to be cloned separately and path to them specified via an environment variable. Is there any reason why this test repository isn't being tracked by a git submodule? This would take away the manual test suite path handling and in the future remove the guessing as to what commit of that repository ought to be used.

[schaze]

This is actually planned.
We were just building up the test repo on the convention side and I did not want any interference in my lib until I was sure it goes somewhere.