LibDraw: Introduce an Emoji class

This class can locate and load emojis, which are expected to be stored
as regular PNG images at /res/emoji/U+XXXX.png, where XXXX is the
character codepoint.

https://github.com/SerenityOS/serenity/issues/490

Libraries/LibDraw/Emoji.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <AK/Types.h>
+#include <AK/NonnullRefPtr.h>
+
+class GraphicsBitmap;
+
+class Emoji {
+ public:
+    ~Emoji() {}
+
+    static const Emoji* emoji_for_codepoint(u32 codepoint);
+    const GraphicsBitmap& bitmap() const { return m_bitmap; }
+
+private:
+    explicit Emoji(NonnullRefPtr<GraphicsBitmap>);
+
+    NonnullRefPtr<GraphicsBitmap> m_bitmap;
+};