[AppService]Support for changing Trigger

[badboy-huaqiao]

app service needs to restart when Trigger is changed, but right now GUI doesn't have the ability to restart this service.

system agent was deprecated and will be removed in furture, that means GUI will not have any ability to restart a service, of course including any app services, GUI needs to provide someting stuff to tell user to restart the app service manually if users want to change the trigger on GUI.