[native] Fix UsernameSelection loading state when usingCommServicesAccessToken

Summary:
@varun didn't consider loading state in D11320, so it was broken when usingCommServicesAccessToken.

Depends on D13310

Test Plan: Make sure loading state works correctly in UsernameSelection

Reviewers: varun, will

Reviewed By: varun

Subscribers: tomek, varun

Differential Revision: https://phab.comm.dev/D13311