LibURL: Add helper for getting array of the special schemes

This is useful for iterating over all of the special schemes, as
needed in the URLPattern implementation.

Libraries/LibURL/URL.cpp

@@ -207,9 +207,23 @@ URL create_with_data(StringView mime_type, StringView payload, bool is_base64)
 }
 
 // https://url.spec.whatwg.org/#special-scheme
+ReadonlySpan<StringView> special_schemes()
+{
+    static auto const schemes = to_array<StringView>({
+        "ftp"sv,
+        "file"sv,
+        "http"sv,
+        "https"sv,
+        "ws"sv,
+        "wss"sv,
+    });
+    return schemes;
+}
+
+// https://url.spec.whatwg.org/#is-special
 bool is_special_scheme(StringView scheme)
 {
-    return scheme.is_one_of("ftp", "file", "http", "https", "ws", "wss");
+    return special_schemes().contains_slow(scheme);
 }
 
 // https://url.spec.whatwg.org/#url-path-serializer

Libraries/LibURL/URL.h

@@ -61,6 +61,7 @@ void append_percent_encoded_if_necessary(StringBuilder&, u32 code_point, Percent
 void append_percent_encoded(StringBuilder&, u32 code_point);
 bool code_point_is_in_percent_encode_set(u32 code_point, PercentEncodeSet);
 Optional<u16> default_port_for_scheme(StringView);
+ReadonlySpan<StringView> special_schemes();
 bool is_special_scheme(StringView);
 
 enum class SpaceAsPlus {