Add window support for Windows.

src/windows/ui_interfaces/win32/Win32Window.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include "IPlatformWindow.h"
+#include <Windows.h>
+
+class Win32ApplicationContext;
+class DesktopManager;
+
+class Win32Window : public IPlatformWindow
+{
+public:
+    Win32Window();
+    virtual ~Win32Window() = default;
+
+    static std::unique_ptr<Win32Window> Create();
+
+    LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam);
+
+    HWND GetHandle() const;
+
+    void SetHandle(HWND handle)
+    {
+        mHandle = handle;
+    }
+
+    int GetCmdShow() const
+    {
+        return mCmdShow;
+    }
+
+    void SetCmdShow(int cmdShow)
+    {
+        mCmdShow = cmdShow;
+    }
+
+    void CreateNative(Win32ApplicationContext* context, DesktopManager* desktopManager);
+
+private:
+    HWND mHandle{ 0 };
+    int mCmdShow{ 0 };
+    DesktopManager* mDesktopManager;
+};