[native] Display the pinned messages for the thread in the new screen

Summary:
This is the screen that should display the pinned messages / the search results.

Logic is similar to web: https://phab.comm.dev/D7380

Depends on D7672

Test Plan:
Check to see the pinned messages render in the screen

Reviewers: atul, ginsu, tomek, ashoat

Reviewed By: atul, ashoat

Subscribers: ashoat, inka

Differential Revision: https://phab.comm.dev/D7673