[native] Move tabNavigator listener to useEffect

Summary:
ENG-1855, raised in this diff
Moves the code from mount methods to a useEffect in the ConnectedThreadSettings.

Test Plan:

• Open thread settings, click on the profile tab
  • click on the "inbox" tab -> you should return to the thread settings
  • click on the "inbox" tab again -> you should return to the chat list
• Open thread settings, change some option, click on the "inbox" tab -> you should return to the chat list but only after the change is saved

Reviewers: tomek, atul, abosh, ashoat

Reviewed By: ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D5202