LibJS+LibUnicode: Fully implement Intl.Collator with ICU

We were never able to implement anything other than a basic, locale-
unaware collator with the JSON export of the CLDR as it did not have
collation data. We can now use ICU to implement collation.

Userland/Libraries/LibUnicode/Collator.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullOwnPtr.h>
+#include <AK/StringView.h>
+
+namespace Unicode {
+
+enum class Usage {
+    Sort,
+    Search,
+};
+Usage usage_from_string(StringView);
+StringView usage_to_string(Usage);
+
+enum class Sensitivity {
+    Base,
+    Accent,
+    Case,
+    Variant,
+};
+Sensitivity sensitivity_from_string(StringView);
+StringView sensitivity_to_string(Sensitivity);
+
+enum class CaseFirst {
+    Upper,
+    Lower,
+    False,
+};
+CaseFirst case_first_from_string(StringView);
+StringView case_first_to_string(CaseFirst);
+
+class Collator {
+public:
+    static NonnullOwnPtr<Collator> create(
+        StringView locale,
+        Usage,
+        StringView collation,
+        Sensitivity,
+        CaseFirst,
+        bool numeric,
+        bool ignore_punctuation);
+
+    virtual ~Collator() = default;
+
+    enum class Order {
+        Before,
+        Equal,
+        After,
+    };
+    virtual Order compare(StringView, StringView) const = 0;
+
+protected:
+    Collator() = default;
+};
+
+}