[native] Fix userInfo calculation in UserAvatar

Summary:
The previous code was passing the wrong userInfo to useENSResolvedAvatar when the userInfo prop was specified. The new code keeps the decision in one place, with only one selector.

Depends on D8086

Test Plan: Make sure we're not randomly using the anonymous user emoji from EditUserAvatar rendered with a userInfo prop

Reviewers: atul, ginsu

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D8087