Have a config option to add the debug API commands

[johannaengland]

After a little discussion with @runborg we decided it might be good to have a config option to disable the debug API commands (anything part of ZinoTestProtocol). That way an API user does not suddenly have more power using the API than before.

We can have a decorator similar to require_authentication that marks an API command as new/debug, which then will not be returned by _get_all_responders.

[lunkwill42]

Well, in reality, the ZinoTestProtocol should not be used by default at all, it's just there during initial development of the API. Its instantiation should be permanently replaced by Zino1ServerProtocol. The question is whether this issue serves to remind us to do this before the Zino 2.0 release, or if it should be a separate issue (now that this is labeled as post-zino-2.0)

What we could consider, however, is a config option to selectively replace the default protocol implementation with something more experimental (like ZinoTestProtocol, if you like)

[lunkwill42]

This is the line that needs to be changed before Zino 2.0:

https://github.com/Uninett/zino/blob/4343bacf96518f769ea4e1a804a23bcfa5b20935/src/zino/api/server.py#L33-L32