[client/idd] input: reduce network latency

Route input through a dedicated high-priority stream, send pointer
motion as cumulative datagrams, and recover suspected loss reliably.

Reduce downstream input queuing with age-aware coalescing and input
thread scheduling.

idd/LGInput/ipc/CInputPipeClient.cpp

@@ -57,7 +57,11 @@ bool CInputPipeClient::Start()
   return m_endpoint.Start(
     LG_INPUT_PIPE_NAME,
     CPipeEndpoint::Mode::Client,
-    sizeof(LGInputPipeMessage));
+    sizeof(LGInputPipeMessage),
+    nullptr,
+    0,
+    0,
+    CPipeEndpoint::ThreadScheduling::Input);
 }
 
 void CInputPipeClient::Stop()