VideoCommon: add some helper functions for resource logic that generates invalid textures for when a texture isn't provided for a custom asset

Source/Core/VideoCommon/Resources/InvalidTextures.h

@@ -0,0 +1,16 @@
+// Copyright 2025 Dolphin Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <memory>
+
+#include "VideoCommon/AbstractTexture.h"
+
+namespace VideoCommon
+{
+std::unique_ptr<AbstractTexture> CreateInvalidTransparentTexture();
+std::unique_ptr<AbstractTexture> CreateInvalidColorTexture();
+std::unique_ptr<AbstractTexture> CreateInvalidCubemapTexture();
+std::unique_ptr<AbstractTexture> CreateInvalidArrayTexture();
+}  // namespace VideoCommon