[ENG-8979](https://linear.app/comm/issue/ENG-8979/logic-for-changing-thread-settings);
Because we can just return empty `ChangeThreadSettingsPayload` we were able to update this here, not in each component. This simplified things a lot, implicitly handled loading status, and saved a lot of other work.
To fully support avatars I created [ENG-9102](https://linear.app/comm/issue/ENG-9102/handle-thread-avatars-in-thick-threads).