added small change to IWindow to be able to get the window size from the interface pointer, and not needing to use glfw for it

TSE_Core/src/interfaces/IWindow.hpp

@@ -2,6 +2,7 @@
 
 #include "IRenderTarget.hpp"
 #include "Types.hpp"
+#include "Vector2.hpp"
 
 namespace TSE
 {
@@ -20,6 +21,7 @@ namespace TSE
 
         bool BaseInit() const;
         void BaseUpdate() const;
+        Vector2 GetSize() const;
         ~IWindow();
     };
 } // namespace TSE