[lib] Search for users in thread list search

Summary:
issue: ENG-7315
We want the search in thread list to start querying the identity service for users

(okapi7 is a user registered on my keyserver)

Test Plan:
Tested that on web and native thread list now also shows users registered with identity that the user does not know of - that are not even on my keyserver
Tested that threads that match the query are still visible as well
Tested that users that are registered with my keyserver are visible

Reviewers: will, tomek, ashoat

Reviewed By: will, ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11799