LibGfx: Add CMYKBitmap

This is a simple container for 2d CMYK data.

This is a new class instead of a new format in Bitmap because:
* Almost all clients of Bitmap will want to deal with RGB data
* It keeps the ARGB32 typedef working
* Bitmap already does a lot of things

The idea is that a few select places will be able to use
CMYKBitmap and a color profile to do a better CMYK -> RGB conversion
than an image decoder could do, and then store the result in a Bitmap
for later display then.

CMYKBitmap misses some of Bitmap's features, such as shared
memory support, high-dpi scaling capability, etc.

Userland/Libraries/LibGfx/CMYKBitmap.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibGfx/CMYKBitmap.h>
+
+namespace Gfx {
+
+ErrorOr<NonnullRefPtr<CMYKBitmap>> CMYKBitmap::create_with_size(IntSize const& size)
+{
+    VERIFY(size.width() >= 0 && size.height() >= 0);
+    auto data = TRY(ByteBuffer::create_uninitialized(size.width() * size.height() * sizeof(CMYK)));
+    return adopt_ref(*new CMYKBitmap(size, move(data)));
+}
+
+}