[native] Let the user dismiss the SIWEPanel with a gesture

Summary: We need to make sure we trigger goBackToPrompt when the user dismisses the BottomSheet.

Test Plan: Dismiss the BottomSheet and make sure LoggedOutModal goes back to the prompt

Reviewers: atul

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D6009