[lib] Update CurrentUserInfo on updateUserAvatarActionTypes.success

Summary: We want to update CurrentUserInfo in Redux on successful updateUserAvatarActionTypes.success.

Test Plan:

1. Observe that avatar is set:

2. Send { type: 'remove' } to update_user_avatar and observe that the avatar is unset in Redux:

3. Send

const emojiUpdateRequest = {
  type: 'emoji',
  emoji: '👍',
  color: '4b87aa',
};

to update_user_avatar and observe that CurrentUserInfo is updated as expected:

Reviewers: ashoat, ginsu

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D7156