libobs: Add ability to get max cx/cy/fps from service

This obs_service_t object callback was implemented specifically for
services which may have a maximum recommended width, height, and
framerate that needs to be enforced.

libobs/obs.h

@@ -2211,6 +2211,9 @@ EXPORT void *obs_service_get_type_data(obs_service_t *service);
 
 EXPORT const char *obs_service_get_id(const obs_service_t *service);
 
+EXPORT void obs_service_get_max_res_fps(const obs_service_t *service, int *cx,
+					int *cy, int *fps);
+
 /* NOTE: This function is temporary and should be removed/replaced at a later
  * date. */
 EXPORT const char *obs_service_get_output_type(const obs_service_t *service);