Feature/support forgot password

lib/src/msal_exception.dart

@@ -37,3 +37,7 @@ class MsalUninitializedException extends MsalException {
       : super(
             "Client not initialized. Client must be initialized before attempting to use");
 }
+
+class MsalForgotPasswordException extends MsalException {
+  MsalForgotPasswordException() : super("User forgot password");
+}

lib/src/public_client_application.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
+
 import 'package:flutter/services.dart';
+
 import 'msal_exception.dart';
 
 /// Represents a PublicClientApplication used to authenticate using the implicit flow
@@ -88,7 +90,17 @@ class PublicClientApplication {
         return MsalInitializationException();
       case "AUTH_ERROR":
       default:
-        return MsalException("Authentication error");
+
+        /// PlatformException(AUTH_ERROR, Authentication error, The operation couldn’t be completed. (MSALErrorDomain error -50000.))
+        /// PlatformException(AUTH_ERROR, Authentication failed, access_denied;AADB2C90118: The user has forgotten their password.
+        var detailsInLowerCase = e.details.toString().toLowerCase();
+        if (e.details != null &&
+            (detailsInLowerCase.contains('msalerrordomain error -50000') ||
+                detailsInLowerCase.contains('aadb2c90118'))) {
+          return MsalForgotPasswordException();
+        } else {
+          return MsalException("Authentication error");
+        }
     }
   }