[native] Memoize swipeableThread in ChatThreadListItem

Summary:
This prevents re-renders of SwipeableThreads. As of this diff we've reduced the time of ChatThreadList re-renders from ~600ms to ~70ms.

ChatThreadListItem before D9102:

ChatThreadListItem before this diff:

ChatThreadListItem after this diff:

(This is the chatThreadListItem for Daily Updates)

Depends on D9102

Test Plan: Things continue to look/work as expected.

Reviewers: ginsu, tomek, rohan

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D9103