LibDraw: Rename ImageLoader => ImageDecoder

ImageLoader was not the right name for this, as there is no loading
happening, only decoding. :^)

Libraries/LibDraw/ImageLoader.h

@@ -1,35 +0,0 @@
-#pragma once
-
-#include <AK/NonnullRefPtr.h>
-#include <AK/OwnPtr.h>
-#include <AK/RefCounted.h>
-#include <LibDraw/Size.h>
-
-class GraphicsBitmap;
-
-class ImageLoaderPlugin {
-public:
-    virtual ~ImageLoaderPlugin() {}
-
-    virtual Size size() = 0;
-    virtual RefPtr<GraphicsBitmap> bitmap() = 0;
-
-protected:
-    ImageLoaderPlugin() {}
-};
-
-class ImageLoader : public RefCounted<ImageLoader> {
-public:
-    static NonnullRefPtr<ImageLoader> create(const u8* data, size_t size) { return adopt(*new ImageLoader(data, size)); }
-    ~ImageLoader();
-
-    Size size() const { return m_plugin->size(); }
-    int width() const { return size().width(); }
-    int height() const { return size().height(); }
-    RefPtr<GraphicsBitmap> bitmap() const { return m_plugin->bitmap(); }
-
-private:
-    ImageLoader(const u8*, size_t);
-
-    mutable OwnPtr<ImageLoaderPlugin> m_plugin;
-};