LibUncode: Parse and generate emoji code point data

According to TR #51, the "best definition of the full set [of emojis] is
in the emoji-test.txt file". This defines not only the emoji themselves,
but the order in which they should be displayed, and what "group" of
emojis they belong to.

Userland/Libraries/LibUnicode/Emoji.cpp

@@ -0,0 +1,13 @@
+/*
+ * Copyright (c) 2022, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibUnicode/Emoji.h>
+
+namespace Unicode {
+
+Optional<Emoji> __attribute__((weak)) find_emoji_for_code_points(Span<u32 const>) { return {}; }
+
+}