Shaped up some VTK subclass's implementations of New()

These were not interacting properly with vtkDebugLeaks because their
New() implementations were not registering when the objects were
allocated.

Common/ExecutionModel/Testing/Cxx/TestMultiOutputSimpleFilter.cxx

@@ -21,7 +21,7 @@ namespace
 class vtkTestAlgorithm : public vtkPassInputTypeAlgorithm
 {
 public:
-  static vtkTestAlgorithm* New() { return new vtkTestAlgorithm; }
+  static vtkTestAlgorithm* New();
   vtkTestAlgorithm(const vtkTestAlgorithm&) = delete;
   void operator=(const vtkTestAlgorithm&) = delete;
 
@@ -88,6 +88,8 @@ protected:
   }
 };
 
+vtkStandardNewMacro(vtkTestAlgorithm);
+
 void AddPerBlockFieldData(vtkCompositeDataSet* data)
 {
   vtkSmartPointer<vtkCompositeDataIterator> iter;

Interaction/Widgets/Testing/Cxx/TestPlaybackWidget.cxx

@@ -32,7 +32,7 @@
 class vtkSubclassPlaybackRepresentation : public vtkPlaybackRepresentation
 {
 public:
-  static vtkSubclassPlaybackRepresentation *New() {return new vtkSubclassPlaybackRepresentation;}
+  static vtkSubclassPlaybackRepresentation *New();
   void Play() override {std::cout << "play\n";}
   void Stop() override {std::cout << "stop\n";}
   void ForwardOneFrame() override {std::cout << "forward one frame\n";}
@@ -41,6 +41,7 @@ public:
   void JumpToEnd() override {std::cout << "jump to end\n";}
 };
 
+vtkStandardNewMacro(vtkSubclassPlaybackRepresentation);
 
 int TestPlaybackWidget(int vtkNotUsed(argc), char *vtkNotUsed(argv)[])
 {