LibGfx/JPEG: Add a JPEG encoder :^)

This encoder is very naive as it only output SOF0 images and uses
pre-defined Huffman tables.

There is also a small bug with quantization which make using it
over-degrade the quality.

Userland/Libraries/LibGfx/ImageFormats/JPEGWriter.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2023, Lucas Chollet <lucas.chollet@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <LibGfx/Forward.h>
+
+namespace Gfx {
+
+class JPEGWriter {
+public:
+    static ErrorOr<void> encode(Stream&, Bitmap const&);
+
+private:
+    JPEGWriter() = delete;
+};
+
+}