[lib] Make relationship update function dependent on user id

Summary:
We don't need to depend on the whole user info and instead can depend only on the id.
This is the first step of extracting a hook that provides functions that manipulate relationships.

Test Plan: It shouldn't change the behavior but still tested it by sending friend request on native and checking if the state was updated.

Reviewers: benschac, atul, def-au1t

Reviewed By: atul

Subscribers: ashoat, Adrian, karol-bisztyga, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3732