[native] identity password login on native

Summary:
can now successfully log in to the identity service from native with username/password if usingCommServicesAccessToken is enabled

Depends on D10828

Test Plan: log in to identity service from native. also check that the correct error message is displayed if a user isn't registered or app is out of date

Reviewers: ashoat, inka, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D10836