LibWeb: Add is_code_unit_prefix() function

Author: https://github.com/networkException
Commit: ee27d8cdfd
Pull-request: https://github.com/SerenityOS/serenity/pull/15758
Reviewed-by: https://github.com/davidot ✅
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/Infra/Strings.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2022, networkException <networkexception@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -11,5 +12,6 @@
 namespace Web::Infra {
 
 String strip_and_collapse_whitespace(StringView string);
+bool is_code_unit_prefix(StringView potential_prefix, StringView input);
 
 }