Show mutual token holdings / communities on user's profile

**Expected Behavior**
If signed in and on a user's profile, show common projects between the authenticated user and the user's profile.

For example, I have a Cool Cat and an MFer.
I land on Vitalik's profile and he has a Cool Cat.
Show me feedback that me and Vitalik have Cool Cats in common.

Start by locating the user profile page and the data used for the signed-in user and displayed profile. Trace how token holdings or communities are loaded, then define completion as showing the shared projects when both users have matching holdings.

Written by the indexing model from the issue text.