message: Add dumps for nGraph clusters
diff: #include "tensorflow/core/util/device_name_utils.h"
  #include "ngraph_cluster_manager.h"
  +#include "ngraph_utils.h"
  using namespace std;
  namespace ngraph_bridge {
  @@ -420,6 +421,13 @@ class NGraphEncapsulatePass : public tensorflow::GraphOptimizationPass {
  tf::GraphConstructorOptions opts;
  opts.allow_internal_ops = true;
  TF_RETURN_IF_ERROR(tf::ConvertGraphDefToGraph(opts, *NGraphClusterManager::GetClusterGraph(cluster_idx), &g));
  +
  + std::stringstream ss;
  + ss << "ngraph_cluster_" << cluster_idx;
  + std::string filename_prefix = ss.str();
  +
  + GraphToPbTextFile(&g, filename_prefix + ".pbtxt");
  + GraphToDotFile(&g, filename_prefix + ".dot", "nGraph Cluster Dump: " + filename_prefix, false);
  }
  }
  