Reset terms of service

Follow up https://gitlab.com/gitlab-org/gitlab-ce/issues/44798, so that from the admin panel, you can reset the terms of service for an instance as an admin, and that would require all users to accept the terms again.

This would be used if the terms need to be updated and you need users to accept the updated version.

As part of this scope, perhaps it makes sense to log:

• Each new version of the updated terms in the database, for auditing reasons.
• Every time a user accepts an updated terms, log in the db which version they accepted, again for auditing reasons.