Redefine ID types to be actual pointers

Redefined various ID types to be aliases of pointers instead of casting
a uintptr_t to the needed pointer.

e.g. SurfaceID = Surface*

engine/include/nova/platform/window_driver.h

@@ -7,17 +7,13 @@
 #pragma once
 
 #include <nova/api.h>
-#include <nova/platform/window_api.h>
+#include <nova/platform/window_fwd.h>
+#include <nova/render/render_fwd.h>
 #include <nova/types.h>
 
 #include <string_view>
 
 namespace Nova {
-	using WindowID = uptr;
-	using SurfaceID = uptr;
-
-	class RenderDriver;
-
 	class NOVA_API WindowDriver {
 	  public:
 		static WindowDriver* create();

engine/include/nova/platform/window_fwd.h

@@ -8,4 +8,9 @@
 
 namespace Nova {
 	enum class WindowAPI { WAYLAND, WINDOWS, X11 };
+
+	class WindowDriver;
+
+	struct Window;
+	using WindowID = Window*;
 } // namespace Nova