[lib][native][web] Introduce useUpdateRelationships

Summary:
This diff updates the updateRelationships action function to use the new update_relationships2 API, and introduces useUpdateRelationships, a new hook that abstracts some complexity and in following diffs will handle forking between thick/thread logic.

Depends on D13440

Test Plan: I tested this new endpoint as part of my testing of ENG-9269

Reviewers: tomek

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D13441