[lib] Basic implementation of identity search context provider without message sending

Summary:
This implements a basic context provider which connects to the identity search service

Depends on D10928

Test Plan: flow and verified connection by writing some basic code on web utilizing context provider

Reviewers: varun, bartek, ashoat, atul

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10938