Summary: when vzmgr receives a vizier connected request, it should broadcast to NATS. for now, I just publish to the "VizierConnected" channel with the vizier's id, org id, and current resource version

Test Plan: unit test

Reviewers: zasgar, #engineering

Reviewed By: zasgar, #engineering

Differential Revision: https://phab.corp.pixielabs.ai/D3717

GitOrigin-RevId: 6b82f02660c3783433757d52353b403a9d68d727