[Auth] Update StartMFAEnrollmentRequest to have only immutable properties

Author: ncooke3

FirebaseAuth/Sources/Swift/Backend/RPC/MultiFactor/Enroll/StartMFAEnrollmentRequest.swift

@@ -24,30 +24,43 @@ class StartMFAEnrollmentRequest: IdentityToolkitRequest, AuthRPCRequest {
   typealias Response = StartMFAEnrollmentResponse
 
   let idToken: String?
-  private(set) var phoneEnrollmentInfo: AuthProtoStartMFAPhoneRequestInfo?
-  private(set) var totpEnrollmentInfo: AuthProtoStartMFATOTPEnrollmentRequestInfo?
+  let phoneEnrollmentInfo: AuthProtoStartMFAPhoneRequestInfo?
+  let totpEnrollmentInfo: AuthProtoStartMFATOTPEnrollmentRequestInfo?
 
-  init(idToken: String?,
-       enrollmentInfo: AuthProtoStartMFAPhoneRequestInfo?,
-       requestConfiguration: AuthRequestConfiguration) {
-    self.idToken = idToken
-    phoneEnrollmentInfo = enrollmentInfo
-    super.init(
-      endpoint: kStartMFAEnrollmentEndPoint,
-      requestConfiguration: requestConfiguration,
-      useIdentityPlatform: true
+  convenience init(idToken: String?,
+                   enrollmentInfo: AuthProtoStartMFAPhoneRequestInfo?,
+                   requestConfiguration: AuthRequestConfiguration) {
+    self.init(
+      idToken: idToken,
+      enrollmentInfo: enrollmentInfo,
+      totpEnrollmentInfo: nil,
+      requestConfiguration: requestConfiguration
     )
   }
 
-  init(idToken: String?,
-       totpEnrollmentInfo: AuthProtoStartMFATOTPEnrollmentRequestInfo?,
-       requestConfiguration: AuthRequestConfiguration) {
+  convenience init(idToken: String?,
+                   totpEnrollmentInfo: AuthProtoStartMFATOTPEnrollmentRequestInfo?,
+                   requestConfiguration: AuthRequestConfiguration) {
+    self.init(
+      idToken: idToken,
+      enrollmentInfo: nil,
+      totpEnrollmentInfo: totpEnrollmentInfo,
+      requestConfiguration: requestConfiguration
+    )
+  }
+
+  private init(idToken: String?,
+               enrollmentInfo: AuthProtoStartMFAPhoneRequestInfo?,
+               totpEnrollmentInfo: AuthProtoStartMFATOTPEnrollmentRequestInfo?,
+               requestConfiguration: AuthRequestConfiguration) {
     self.idToken = idToken
+    phoneEnrollmentInfo = enrollmentInfo
     self.totpEnrollmentInfo = totpEnrollmentInfo
     super.init(
       endpoint: kStartMFAEnrollmentEndPoint,
       requestConfiguration: requestConfiguration,
-      useIdentityPlatform: true
+      useIdentityPlatform: true,
+      useStaging: false
     )
   }