feat: Implement Windows runner for Flutter application

- Added FlutterWindow class to manage the Flutter view within a Win32 window.
- Created main entry point in main.cpp to initialize and run the Flutter application.
- Implemented utility functions for console attachment and command line argument parsing.
- Added resource management for application icon and manifest.
- Enhanced Win32Window class for DPI awareness and theme management.
- Included necessary headers and resource files for building the Windows runner.

linux/runner/my_application.h

@@ -0,0 +1,18 @@
+#ifndef FLUTTER_MY_APPLICATION_H_
+#define FLUTTER_MY_APPLICATION_H_
+
+#include <gtk/gtk.h>
+
+G_DECLARE_FINAL_TYPE(MyApplication, my_application, MY, APPLICATION,
+                     GtkApplication)
+
+/**
+ * my_application_new:
+ *
+ * Creates a new Flutter-based application.
+ *
+ * Returns: a new #MyApplication.
+ */
+MyApplication* my_application_new();
+
+#endif  // FLUTTER_MY_APPLICATION_H_