message: Add API for bulk-setting attributes in an OperationState
  This API is needed for the TFLite flatbuffer importer as the importer constructs
  arrays of NamedAttributes based on the flatbuffer that need to be added to an
  operation.
diff: @@ -287,6 +287,11 @@ public:
  attributes.push_back({name, attr});
  }
  + /// Add an array of named attributes.
  + void addAttributes(ArrayRef<NamedAttribute> newAttributes) {
  + attributes.append(newAttributes.begin(), newAttributes.end());
  + }
  +
  void addSuccessor(Block *successor, ArrayRef<Value *> succOperands) {
  successors.push_back(successor);
  // Insert a sentinal operand to mark a barrier between successor operands.
  