BDD: add create ContentTypeGroup feature and sentences to interfaces

The new idea to centralize sentences (at least the community/high level sentences)

Defining the sentences on the interfaces (function names that will match those sentences)
this way it will make that any implementation for a new API/browser interface will have to have those functions implemented, and the sentences definitions will be also centralized, so that there are no repetition, or wrong matches.

Benefits:
- obligate the tests for the a new interface to be complete
- centralized sentences (separated by type)
- interface will make an easy way for community to look into sentences (almost no documentation need)