[net processing] Move ping data fields to net processing

src/net_processing.h

@@ -30,6 +30,7 @@ struct CNodeStateStats {
     int nSyncHeight = -1;
     int nCommonHeight = -1;
     int m_starting_height = -1;
+    int64_t m_ping_wait_usec;
     std::vector<int> vHeightInFlight;
 };
 
@@ -47,6 +48,9 @@ public:
     /** Whether this node ignores txs received over p2p. */
     virtual bool IgnoresIncomingTxs() = 0;
 
+    /** Send ping message to all peers */
+    virtual void SendPings() = 0;
+
     /** Set the best height */
     virtual void SetBestHeight(int height) = 0;