974712: Content View Filter: improve behavior for repo section

This commit provides a couple of small changes to help improve
the user behavior for filters:

1. when user opens a filter, if it doesn't have any products
   or repositories assigned to it, make the 'Repositories'
   tab the 'active' tab

2. when user goes to the 'Rules' tab, if there aren't any
   products or repositories assigned, present the user a warning
   that they need to add one.