added Type Jam puzzle app for review (#1554)

* added Type Jam puzzle app for review

* pr round 2 prep

* updated ci scripts for varfont_shader_puzzle

* resolved unused and minor variable naming issues

* rotator tiles row and col are final vars now

* removed unused import and print from production

* made constructors const where needed

* pages_flow export refactored to directly come from that file

* removed old api commented out section from FragmentShaded

* updated pubspec yaml to correct project name

* dart min version updated; removed unnecessary commented out dependencies from pubspec.yaml

* updated pubspec.yaml min flutter version to ensure FragmentShader support

* added/edited comments for explanation, esp on var fonts; removed obsolete comments

* trailing newline added to pubspec.yaml eof

experimental/varfont_shader_puzzle/windows/runner/flutter_window.h

@@ -0,0 +1,33 @@
+#ifndef RUNNER_FLUTTER_WINDOW_H_
+#define RUNNER_FLUTTER_WINDOW_H_
+
+#include <flutter/dart_project.h>
+#include <flutter/flutter_view_controller.h>
+
+#include <memory>
+
+#include "win32_window.h"
+
+// A window that does nothing but host a Flutter view.
+class FlutterWindow : public Win32Window {
+ public:
+  // Creates a new FlutterWindow hosting a Flutter view running |project|.
+  explicit FlutterWindow(const flutter::DartProject& project);
+  virtual ~FlutterWindow();
+
+ protected:
+  // Win32Window:
+  bool OnCreate() override;
+  void OnDestroy() override;
+  LRESULT MessageHandler(HWND window, UINT const message, WPARAM const wparam,
+                         LPARAM const lparam) noexcept override;
+
+ private:
+  // The project to run.
+  flutter::DartProject project_;
+
+  // The Flutter instance hosted by this window.
+  std::unique_ptr<flutter::FlutterViewController> flutter_controller_;
+};
+
+#endif  // RUNNER_FLUTTER_WINDOW_H_