AK: Implement UTF-16 string-to-number conversions

Author: https://github.com/trflynn89
Commit: d40e3af697
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5388
Reviewed-by: https://github.com/shannonbooth ✅

AK/Utf16View.h

@@ -14,6 +14,7 @@
 #include <AK/Optional.h>
 #include <AK/Span.h>
 #include <AK/String.h>
+#include <AK/StringConversions.h>
 #include <AK/StringHash.h>
 #include <AK/Traits.h>
 #include <AK/Types.h>
@@ -210,6 +211,14 @@ public:
         return { m_string.utf16, length_in_code_units() };
     }
 
+    template<Arithmetic T>
+    ALWAYS_INLINE Optional<T> to_number(TrimWhitespace trim_whitespace = TrimWhitespace::Yes) const
+    {
+        if (has_ascii_storage())
+            return parse_number<T>(bytes(), trim_whitespace);
+        return parse_number<T>(*this, trim_whitespace);
+    }
+
     [[nodiscard]] constexpr bool operator==(Utf16View const& other) const
     {
         if (length_in_code_units() != other.length_in_code_units())