[identity] use identitySearchSocket instead of socket.current

Summary:
This addresses https://linear.app/comm/issue/ENG-9971/[error-invalid-state-err]-in-identitysearchprovider

We should be using identitySearchSocket instead of socket.current could be null before we properly set it

Test Plan:
cargo check

Didn't get to testing this properly. Putting up this diff for now to get it into review, but I'll ensure we're not getting spammed with:

ERROR  [Error: INVALID_STATE_ERR]

before landing

Reviewers: kamil, varun, ashoat

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D14094