Add api and methods to allow followers and discussions

[nicolaskempf57]

Required for https://github.com/datagouv/data.gouv.fr/issues/1369

[ThibaudDauce]

I don't see the controller for Discussion (only for Followers), am I missing something? (but I can add latter it if you've only added the minimal requirements to not crash on the frontend I understand :-D )

[nicolaskempf57]

I don't see the controller for Discussion (only for Followers), am I missing something? (but I can add latter it if you've only added the minimal requirements to not crash on the frontend I understand :-D )

You're right, there is no controller for discussions, it's handled in udata/core/discussions/api.py only.

[maudetes]

As a reference, when creating discussions on topics object, we had to make these two fixes:

• https://github.com/opendatateam/udata/pull/2922
• https://github.com/opendatateam/udata/pull/2944