Initial work to add the SQLite plugin and builtin recipient

scripts/lua/get_notification_configs.lua

@@ -19,4 +19,13 @@ end
 
 local endpoints = notification_configs.get_configs()
 
-print(json.encode(endpoints))
+-- Exclude builtin configs
+-- Such configs will be possibly made non-editable non-deletable later
+local res = {}
+for _, config in pairs(endpoints) do
+   if not config.endpoint_conf.builtin then
+      res[#res + 1] = config
+   end
+end
+
+print(json.encode(res))