[native] update thread notif settings ui to handle case when parent thread is in background

Summary:
If a thread's parent is in in the background, then instead of showing our usual interface we show a prompt to the user telling them that they can't update the notification settings. We also don't render the save button

Depends on D12662

Test Plan:
Please see the screenshot below

Reviewers: ashoat, inka

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12663