libobs: Add ability to create private services

This is a band-aid solution to be able to create temporary services
without logging them and keep them out of enumeration functions.

This is a band-aid solution -- 'master obs context lists' should not be
kept by the core.  Logging of object creation/destruction should also be
controlled by the front-end instead of the core.

libobs/obs.h

@@ -1648,6 +1648,9 @@ EXPORT const char *obs_service_get_display_name(const char *id);
 EXPORT obs_service_t *obs_service_create(const char *id, const char *name,
 		obs_data_t *settings, obs_data_t *hotkey_data);
 
+EXPORT obs_service_t *obs_service_create_private(const char *id,
+		const char *name, obs_data_t *settings);
+
 /**
  * Adds/releases a reference to a service.  When the last reference is
  * released, the service is destroyed.