message: Fix bug in delegating partial subgraphs to XNNPACK
  Delegation of partial subgraphs with DENSIFY or FP16 DEQUANTIZE nodes could be
  broken due to using wrong index (index within the execution plan rather than
  a global node index) throughout the delegate.
diff: @@ -2915,8 +2915,8 @@ TfLiteIntArray* Delegate::PrepareOpsToDelegate(TfLiteContext* context) {
  if (input_tensor.allocation_type == kTfLiteMmapRo &&
  input_tensor.type == kTfLiteFloat16 &&
  output_tensor.type == kTfLiteFloat32) {
  - static_unpack_nodes_.insert(i);
  - quasi_static_tensors_producers[node->outputs->data[0]] = i;
  + static_unpack_nodes_.insert(node_index);
  + quasi_static_tensors_producers[node->outputs->data[0]] = node_index;
  quasi_static_tensors.insert(node->outputs->data[0]);
  // Skip this node for now. If output of the node is consumed only by
  @@ -2940,8 +2940,8 @@ TfLiteIntArray* Delegate::PrepareOpsToDelegate(TfLiteContext* context) {
  input_tensor.sparsity != nullptr &&
  input_tensor.type == kTfLiteFloat32 &&
  output_tensor.type == kTfLiteFloat32) {
  - static_unpack_nodes_.insert(i);
  - quasi_static_tensors_producers[node->outputs->data[0]] = i;
  + static_unpack_nodes_.insert(node_index);
  + quasi_static_tensors_producers[node->outputs->data[0]] = node_index;
  quasi_static_tensors.insert(node->outputs->data[0]);
  // Skip this node for now. If output of the node is consumed only by
  