Add whitelist for login redirect.

Use LOGIN_REDIRECT_WHITELIST to provide a whitelist of
additional domains to which login will now redirect.

ARCH-238

lms/envs/devstack.py

@@ -228,6 +228,8 @@ CORS_ALLOW_CREDENTIALS = True
 CORS_ORIGIN_WHITELIST = ()
 CORS_ORIGIN_ALLOW_ALL = True
 
+LOGIN_REDIRECT_WHITELIST = []
+
 ###################### JWTs ######################
 JWT_AUTH.update({
     'JWT_ISSUER': OAUTH_OIDC_ISSUER,