Add tabs to view follow relations on the admin federation view (resolves #648)

What does this PR do?

Adds two new tabs to the administrative view of a remote instance:

• Following - shows unique local users who follow a user from the remote instance.
• Followers - shows unique remote users who follow a user from the local instance.

Contribution Guidelines By submitting this merge request, you agree to follow our Contribution Guidelines

• I agree to follow this project's Contribution Guidelines
• I have made sure to test this pull request

added enhancement label

enabled an automatic merge when all merge checks for 046ef599 pass

added 24 commits

• 046ef599...6d7c7357 - 23 commits from branch TransFem-org:develop
• 813e2eeb - Merge branch 'develop' into hazelnoot/648-view-follow-relations

Compare with previous version

I think I want to rework this a bit. The view will be more useful if it shows both sides of the relation.

Superseded by !665 (merged), which is a better solution.

closed