IoUringAssmEngn: add assembleFrameReq

Invoke it instimFrameProductionTimesliceInd.

Also, we discovered:
* stream_descriptor::release() doesn't fully release all metadata
  from the fd it was assigned. This suggests that we should go
  through the codebase and do: release()=>reset() whenever we
  wish to release().
* We've confirmed that spinlocks can be used to prevent race
  conditions between stop() and handler methods.

stimBuffApis/livoxGen1/livoxGen1.h

@@ -30,6 +30,8 @@ struct LivoxProto1DllState
 
 extern LivoxProto1DllState livoxProto1;
 
+extern const SmoCallbacks* smoHooksPtr;
+
 } // namespace stim_buff
 } // namespace smo