[native] introduce thread avatar camera modal

Summary:
Introduce thread avatar camera modal

Depends on D7645

Test Plan: Able to set an image thread avatar through the camera roll. Tested other cases like closing out of the camera modal and everything works as expected

Reviewers: ashoat, atul

Reviewed By: ashoat

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7646