[native] Pull EditAvatarBadge into its own component

Summary:
Pulling out some more that's in common between EditUserAvatar and EditThreadAvatar.

Depends on D7499

Test Plan: Things continue to work and look as expected.

Reviewers: ashoat, ginsu

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D7502