PLUGIN_KI_USER_REQUEST
Direction: plugin to client
When: response to PLUGIN_KI_SERVER_REQUEST
, if the plugin cannot answer the server's auth prompts without presenting prompts of its own to the user
What happens next: the client will send PLUGIN_KI_USER_RESPONSE
Message contents after the type code: exactly the same as in PLUGIN_KI_SERVER_REQUEST
(see section H.6.7).