ncm-metaconfig: Use CAF::TextRender for rendering

This includes moving some of the unittests to CAF::TextRender (but all functionality remains tested)
These tests don't belong with metaconfig anymore. They exercise functionality of `CAF::Render`. I'd either mock `CAF::TextRender` or render just one file of one arbitrary format to ensure the parameter is passed correctly. 

Feel free to move these tests to `CAF` if you think they add any value there, but they can be removed from this module.