[native] use identity wallet login in fullscreen-siwe-panel

Summary: if usingCommServicesAccessToken, SIWE auth will now be done by the identity service

Test Plan:
tested the following cases:

• fresh eth wallet with enableNewRegistrationMode
  • was navigated to the new registration wizard
• existing account with enableNewRegistrationMode
  • was logged in
• fresh eth wallet with !enableNewRegistrationMode
  • was registered with identity service
• existing account with !enableNewRegistrationMode
  • was logged in
• invalid siwe signature
  • alert displayed

handling reserved users will be tackled in https://linear.app/comm/issue/ENG-4033/update-clients-to-try-new-registration-after-failed-login-due-to

Reviewers: tomek, inka, ashoat

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D11005