Move request for notifications permissions to HomeReadyScreen (#3977)

* cleanup the current logic

* add statsig logs

* implement requests for permissions where needed

* oops

* let `addPushTokenListener` handle the token registration

* place new log event type with the other `notifications` type

* place registration next to handler

* more organization

* only call `gate()` if permission is not yet granted

* be more specific to prevent gate pollution

* nit

* make `token` non-optional in `registerToken`

* remove `prevDid`, move `registerPushToken` into `useEffect`

* keep it outside actually

* nit

src/lib/statsig/gates.ts

@@ -5,6 +5,7 @@ export type Gate =
   | 'disable_poll_on_discover_v2'
   | 'dms'
   | 'reduced_onboarding_and_home_algo'
+  | 'request_notifications_permission_after_onboarding'
   | 'show_follow_back_label_v2'
   | 'start_session_with_following_v2'
   | 'test_gate_1'