chore: fix name of challenge to match with SDK changes and updated state machine

Author: khatruong2009

packages/auth/amplify_auth_cognito_dart/lib/src/flows/constants.dart

@@ -58,7 +58,7 @@ abstract class CognitoConstants {
   static const challengeParamSmsMfaCode = 'SMS_MFA_CODE';
 
   /// The `EMAIL_MFA_CODE` parameter.
-  static const challengeParamEmailMfaCode = 'EMAIL_MFA_CODE';
+  static const challengeParamEmailMfaCode = 'EMAIL_OTP_CODE';
 
   /// The `SOFTWARE_TOKEN_MFA_CODE` parameter.
   static const challengeParamSoftwareTokenMfaCode = 'SOFTWARE_TOKEN_MFA_CODE';

packages/auth/amplify_auth_cognito_dart/lib/src/state/machines/sign_in_state_machine.dart

@@ -211,7 +211,7 @@ final class SignInStateMachine
           (type) => switch (type) {
             'SOFTWARE_TOKEN_MFA' => MfaType.totp,
             'SMS_MFA' => MfaType.sms,
-            'EMAIL_MFA' => MfaType.email,
+            'EMAIL_OTP' => MfaType.email,
             _ => () {
                 logger.error('Unrecognized MFA type: $type');
                 return null;
@@ -326,6 +326,8 @@ final class SignInStateMachine
         createSmsMfaRequest(event),
       ChallengeNameType.softwareTokenMfa when hasUserResponse =>
         createSoftwareTokenMfaRequest(event),
+      ChallengeNameType.emailOtp when hasUserResponse =>
+        createEmailMfaRequest(event),
       ChallengeNameType.selectMfaType when hasUserResponse =>
         createSelectMfaRequest(event),
       ChallengeNameType.mfaSetup when hasUserResponse =>
@@ -686,7 +688,7 @@ final class SignInStateMachine
           CognitoConstants.challengeParamAnswer: switch (selection) {
             'sms' => 'SMS_MFA',
             'totp' => 'SOFTWARE_TOKEN_MFA',
-            'email' => 'EMAIL_MFA',
+            'email' => 'EMAIL_OTP',
             _ => throw ArgumentError('Must be either SMS, Email, or TOTP'),
           },
         })
@@ -954,6 +956,7 @@ final class SignInStateMachine
             accessToken: accessToken,
             sms: enableMfaType == MfaType.sms ? MfaPreference.enabled : null,
             totp: enableMfaType == MfaType.totp ? MfaPreference.enabled : null,
+            email: enableMfaType == MfaType.email ? MfaPreference.enabled : null,
           );
         } on Exception catch (e, st) {
           logger.error(

packages/authenticator/amplify_authenticator/lib/src/l10n/generated/input_localizations.dart

@@ -297,6 +297,12 @@ abstract class AuthenticatorInputLocalizations {
   /// **'Authenticator App (TOTP)'**
   String get selectTotp;
 
+  /// Label for the radio button to select email as the user's chosen MFA method.
+  /// 
+  /// In en, this message translates to:
+  /// **'Email'**
+  String get selectEmail;
+
   /// The instructional text for submitting a TOTP pass code
   ///
   /// In en, this message translates to:

packages/authenticator/amplify_authenticator/lib/src/l10n/generated/input_localizations_en.dart

@@ -153,6 +153,9 @@ class AuthenticatorInputLocalizationsEn
   @override
   String get selectTotp => 'Authenticator App (TOTP)';
 
+  @override
+  String get selectEmail => 'Email';
+
   @override
   String get totpCodePrompt =>
       'Please enter the code from your registered Authenticator app';

packages/authenticator/amplify_authenticator/lib/src/l10n/input_resolver.dart

@@ -33,6 +33,7 @@ enum InputField {
   rememberDevice,
   selectSms,
   selectTotp,
+  selectEmail,
   totpCodePrompt,
   usernameType,
 }
@@ -171,6 +172,11 @@ class InputResolverKey {
     field: InputField.selectSms,
   );
 
+  static const selectEmail = InputResolverKey._(
+    InputResolverKeyType.title,
+    field: InputField.email,
+  );
+
   static const totpCodePrompt = InputResolverKey._(
     InputResolverKeyType.title,
     field: InputField.totpCodePrompt,
@@ -456,6 +462,8 @@ class InputResolver extends Resolver<InputResolverKey> {
         return AuthenticatorLocalizations.inputsOf(context).selectSms;
       case InputField.selectTotp:
         return AuthenticatorLocalizations.inputsOf(context).selectTotp;
+      case InputField.selectEmail:
+        return AuthenticatorLocalizations.inputsOf(context).selectEmail;
       case InputField.totpCodePrompt:
         return AuthenticatorLocalizations.inputsOf(context).totpCodePrompt;
       case InputField.usernameType: