[native] introduce nav logic for ThreadSettingsNotifications

Summary:
For the new thread notif settings we decided that we want this user experience to have it's own page. This diff introduces the nave logic needed for this

Linear task: https://linear.app/comm/issue/ENG-7776/improve-thread-notifications-settings-user-experience

Test Plan: Confirmed that I can navigate to this screen

Reviewers: ashoat, inka

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12642