Add DSR packet count to state and qlog.

Summary: It's useful at the end of a connection to know if we tried DSR.

Reviewed By: jbeshay

Differential Revision: D30545282

fbshipit-source-id: bbb2f3408f7a2d5666676c9e2583bf8fd9f18911

quic/dsr/frontend/WriteFunctions.cpp

@@ -87,6 +87,7 @@ uint64_t writePacketizationRequest(
         // used, so setting it to 0
         0,
         true /* isDSRPacket */);
+    connection.dsrPacketCount++;
 
     if (instructionAddError) {
       // TODO: Support empty write loop detection