[native] implement creating olm session with own devices

Summary:
Code that fetches all devices of the user, creates outbound session with each of them, and sends an encrypted message via Tunnelbroker

Depends on D10380

Test Plan: Call this method and verify result

Reviewers: marcin, varun, michal

Reviewed By: marcin

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10381