Add prompt and HD settings to the Google OAuth2 plugin.

config/site_settings.yml

@@ -255,6 +255,14 @@ login:
     default: false
   google_oauth2_client_id: ''
   google_oauth2_client_secret: ''
+  google_oauth2_prompt:
+    default: 'none'
+    type: enum
+    choices:
+      - 'none'
+      - 'consent'
+      - 'select_account'
+  google_oauth2_hd: ''
   enable_yahoo_logins:
     client: true
     default: false

lib/auth/google_oauth2_authenticator.rb

@@ -59,7 +59,9 @@ class Auth::GoogleOAuth2Authenticator < Auth::Authenticator
               strategy.options[:client_id] = SiteSetting.google_oauth2_client_id
               strategy.options[:client_secret] = SiteSetting.google_oauth2_client_secret
            },
-           skip_jwt: true
+           skip_jwt: true,
+           prompt: SiteSetting.google_oauth2_prompt,
+           hd: SiteSetting.google_oauth2_hd
   end
 
   protected