[native] introduce UserProfileBottomSheetNavigator

Summary:
In order to navigate to User Profile Avatar Modal from our user profile bottom sheet we need to introduce a new overlay navigator (this should be an overlay navigator since we want to layer the User Profile Avatar Modal on top of the User Profile Bottom sheet)

This is step 3 in the list below
Outlined below are the steps I will take in this stack (each point here will be it's own diff):

1. Replace out of box BottomSheetModal with basic BottomSheet (Unfortunately, BottomSheetModal does not play nice with nested navigator)
2. Polish up the BottomSheetBackdrop animation
3. Introduce User Profile Bottom Sheet Navigators (this is so we can navigate to User Profile Avatar Modal from the User Profile Bottom Sheet)
4. Introduce the User Profile Avatar Modal component and all the necessary things (like route names) that we will need to navigate to this new screen
5. Factor out the User Avatar component in UserProfile into it's own separate component to keep things better organized

Depends on D9374

Test Plan:
Confirmed that I was able to navigate to the user profile bottom sheet with this new nested navigator and I was able to navigate to the User Profile Avatar (which will be introduced in a subsequent diff)

Reviewers: atul, inka

Reviewed By: atul

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9375