Move Thunder CE display configs into thunder submodule

1)

I've tried moving them now, but somehow the functional test keeps protesting. I would like to postpone this until after the last (gallery) paragraph is converted to a kernel test.

2)

Make sure the config is usable on a 'bare' Thunder install. Test it.

If necessary, strip down the current custom_elements_test_paragraphs to have only thunder related config. Remove the recently added config/install files for strange fields, from them.