[native] Unify thread settings accessibility

Summary:
ENG-1827
Makes sure that both ios and android use the same logic for determining whether the thread settings should be accessible.

Test Plan:
Test on both android and ios

1. Start creating a new thread, the settings should be unavailable
2. Add new users, send a message. Settings should be available when the thread stops being pending.

Reviewers: tomek, atul, abosh, ashoat

Reviewed By: tomek, atul, ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D5219