[shared] [identity] Move search result to response and add ids

Summary:
These changes prepare the context handler to resolve search query promises.

This introduces ids to search queries and responses and introduces the search response type which is now composed a successful search result or an error. The ids are used to match queries to responses in the client.

Further explanation: https://linear.app/comm/issue/ENG-5505/implement-contextprovider-pattern-for-web-socket-connection-status#comment-2162a512

Depends on D10980

Test Plan: cargo build and test on local dev

Reviewers: bartek, varun

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10981