LibJS+LibUnicode: Separate number formatting methods from Locale.h

Currently, we generate separate data files for locale and number format
related tables/methods, but provide public accessors for all of the data
in one Locale.h file. Rather than continuing this trend for date-time,
relative time, etc. formatting, it's a bit easier to reason about if the
public accessors are also in separate files.

Userland/Libraries/LibUnicode/NumberFormat.h

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2021, Tim Flynn <trflynn89@pm.me>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Optional.h>
+#include <AK/String.h>
+#include <AK/StringView.h>
+#include <AK/Vector.h>
+#include <LibUnicode/Forward.h>
+
+namespace Unicode {
+
+struct NumberGroupings {
+    u8 primary_grouping_size { 0 };
+    u8 secondary_grouping_size { 0 };
+};
+
+enum class StandardNumberFormatType : u8 {
+    Decimal,
+    Currency,
+    Accounting,
+    Percent,
+    Scientific,
+};
+
+enum class CompactNumberFormatType : u8 {
+    DecimalLong,
+    DecimalShort,
+    CurrencyUnit,
+    CurrencyShort,
+};
+
+struct NumberFormat {
+    enum class Plurality : u8 {
+        Other,
+        Zero,
+        Single,
+        One,
+        Two,
+        Few,
+        Many,
+    };
+
+    u8 magnitude { 0 };
+    u8 exponent { 0 };
+    Plurality plurality { Plurality::Other };
+    StringView zero_format {};
+    StringView positive_format {};
+    StringView negative_format {};
+    Vector<StringView> identifiers {};
+};
+
+Optional<StringView> get_number_system_symbol(StringView locale, StringView system, StringView symbol);
+Optional<NumberGroupings> get_number_system_groupings(StringView locale, StringView system);
+Optional<NumberFormat> get_standard_number_system_format(StringView locale, StringView system, StandardNumberFormatType type);
+Vector<NumberFormat> get_compact_number_system_formats(StringView locale, StringView system, CompactNumberFormatType type);
+Vector<NumberFormat> get_unit_formats(StringView locale, StringView unit, Style style);
+Optional<NumberFormat> select_pattern_with_plurality(Vector<NumberFormat> const& formats, double number);
+Optional<String> augment_currency_format_pattern(StringView currency_display, StringView base_pattern);
+
+}