Fix window title (everything use unicode)

Juliet/src/Core/HAL/Display/Win32/Win32DisplayEvent.cpp

@@ -155,7 +155,7 @@ namespace Juliet::Win32
         auto* windowState = GetWindowStateFromHandle(handle);
         if (!windowState)
         {
-            return CallWindowProcA(DefWindowProcA, handle, message, wParam, lParam);
+            return CallWindowProc(DefWindowProc, handle, message, wParam, lParam);
         }
 
         switch (message)
@@ -267,6 +267,6 @@ namespace Juliet::Win32
             return returnCode;
         }
 
-        return CallWindowProcA(DefWindowProcA, handle, message, wParam, lParam);
+        return CallWindowProc(DefWindowProc, handle, message, wParam, lParam);
     }
 } // namespace Juliet::Win32

Juliet/src/Core/HAL/Display/Win32/Win32Window.cpp

@@ -43,7 +43,7 @@ namespace Juliet::Win32
     bool CreatePlatformWindow(NonNullPtr<DisplayDevice> self, NonNullPtr<Window> window)
     {
         // TODO : save the instance in app state or something
-        HINSTANCE instance = GetModuleHandle(NULL);
+        HINSTANCE instance = GetModuleHandle(nullptr);
 
         // TODO : Put outside, we should not create a new class for each new window
         WNDCLASSEX WindowClass   = {};