[native] Update iOS badge for rescinds

Summary:
This resolves ENG-5452.

@marcin and I pair-programmed this solution together.

Test Plan: I tested both rescinds, badge-only notifs, and normal notifs in my local environment on the iOS simulator. They all worked correctly

Reviewers: marcin, atul

Reviewed By: atul

Subscribers: tomek, wyilio, marcin

Differential Revision: https://phab.comm.dev/D9600