examples: New example with custom strategy "random-load-balancer-strategy"

Based on Steve DiBenedetto's tutorial code https://github.com/dibenede/ndn-tutorial-gec21
diff --git a/examples/ndn-load-balancer/random-load-balancer-strategy.hpp b/examples/ndn-load-balancer/random-load-balancer-strategy.hpp
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+++ b/examples/ndn-load-balancer/random-load-balancer-strategy.hpp
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+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014,  Regents of the University of California,
+ *                      Arizona Board of Regents,
+ *                      Colorado State University,
+ *                      University Pierre & Marie Curie, Sorbonne University,
+ *                      Washington University in St. Louis,
+ *                      Beijing Institute of Technology,
+ *                      The University of Memphis
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NDNSIM_EXAMPLES_NDN_LOAD_BALANCER_RANDOM_LOAD_BALANCER_STRATEGY_HPP
+#define NDNSIM_EXAMPLES_NDN_LOAD_BALANCER_RANDOM_LOAD_BALANCER_STRATEGY_HPP
+
+#include <boost/random/mersenne_twister.hpp>
+#include "face/face.hpp"
+#include "fw/strategy.hpp"
+
+namespace nfd {
+namespace fw {
+
+class RandomLoadBalancerStrategy : public Strategy {
+public:
+  RandomLoadBalancerStrategy(Forwarder& forwarder, const Name& name = STRATEGY_NAME);
+
+  virtual ~RandomLoadBalancerStrategy();
+
+  virtual void
+  afterReceiveInterest(const Face& inFace, const Interest& interest,
+                       shared_ptr<fib::Entry> fibEntry, shared_ptr<pit::Entry> pitEntry);
+
+public:
+  static const Name STRATEGY_NAME;
+
+protected:
+  boost::random::mt19937 m_randomGenerator;
+};
+
+} // namespace fw
+} // namespace nfd
+
+#endif // NDNSIM_EXAMPLES_NDN_LOAD_BALANCER_RANDOM_LOAD_BALANCER_STRATEGY_HPP