Follow list activation should be by feed instead of overall

Summary

Currently, a follow list can be active (used for feeds) or inactive (not used for feeds). We need this to be by feed, so that each user's feed has it own list of active follow lists. We also need some follow lists to be activated across all feeds a user owns with a simple button.

How should this be managed in the UI? It would be good if the Feed Management page supports activating follow lists for the feed. This could be done exactly the same way as assigning feed generators to the feed. We can switch to the pattern of assigning a follow list to a feed using a button and a dialog, and displaying the list of assigned follow lists.

We also need to support assigning follow lists from another user to current user's feed. We need to support that in the dialog and display in the list who is the creator of each assigned follow list.

Is this a new feature?

• Yes, this is a new feature
• No, this is a change to existing functionality

Description of existing functionality

A follow list has a active flag. In the Follow Lists page, a user can see their follow lists and activate / deactivate them. This is no longer sufficient. We need this activation to be separate for each user's feed. We also need a simple way to activate or deactivate a follow list for all user's feeds.