Enables a test session for SIM-less testing.
Must be called only once per app instance; subsequent calls will reject with
error code pnv/test-session-already-enabled.
Parameters
token: string
The test token generated from the Firebase Console.
Returns Promise<void>
Remarks
In test mode, phone numbers follow the format: valid country code followed by all zeros.
Requires a test token generated from the Firebase Console (7-day TTL).
Throws
pnv/test-session-already-enabled if called more than once.
Throws
pnv/invalid-test-number-id if the token is empty, expired, or duplicated.
Enables a test session for SIM-less testing. Must be called only once per app instance; subsequent calls will reject with error code
pnv/test-session-already-enabled.