Retrieve a FIDO registration.

Retrieve a FIDO registration.

Entitlements:
- manageEnrollMFAMethodAnyUser (Manage second-factor authentication enrollment for all users)
- manageEnrollMFAMethod (Manage own second-factor authentication enrollment)
- readEnrollMFAMethodAnyUser (Read second-factor authentication enrollment for all users)
- readEnrollMFAMethod (Read own second-factor authentication enrollment)