[identity] [3/n] move websocket response functions to send.rs
Summary:
This moves websocket response functions to send.rs for organization purposes
Depends on D10804
Test Plan: cargo run server runs the websocket server successfully
Reviewers: varun, bartek
Reviewed By: bartek
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D10847