Add AzureADOauth2 backend using the v2.0 API.

AzureADOAuth2 uses the v1.0 API which doesn't support personal accounts.
Updating the endpoints used by the original class may break backward
compatibility, so add this as just an additional subclass.

social_core/backends/azuread.py

@@ -145,3 +145,13 @@ def get_auth_token(self, user_id):
             new_token_response = self.refresh_token(token=access_token)
             access_token = new_token_response["access_token"]
         return access_token
+
+class AzureADOAuth2V2(AzureADOAuth2):
+    """ Version of the AzureADOAuth2 backend that uses the v2.0 API endpoints,
+    supporting users with personal Microsoft accounts, if the app settings
+    allow them. """
+
+    name = "azuread-oauth2-v2"
+    AUTHORIZATION_URL = "{base_url}/oauth2/v2.0/authorize"
+    ACCESS_TOKEN_URL = "{base_url}/oauth2/v2.0/token"
+    DEFAULT_SCOPE = ["User.Read profile openid email"]