Add use ens avatar to the edit user avatar action sheet. This diff also introduces useENSUserAvatar to avatar-hooks which handles the logic for saving the ens avatar into our db.

I am aware I wrote useENSUserAvatar with a bit of a naive approach, but I think the goal should be to get things working first so we can get something shipped, then make things more elegant.

Followed the test plan from D7462 and was able to get all the same behavoir/results