AK+LibWeb: Add a UTF-16 starts/ends with wrapper for a single code unit

Author: https://github.com/trflynn89
Commit: 1bc80848fb
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5746
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/HTML/Dates.cpp

@@ -55,7 +55,7 @@ bool is_valid_week_string(Utf16View const& value)
         if (!is_ascii_digit(digit))
             return false;
 
-    if (!parts[1].starts_with("W"sv))
+    if (!parts[1].starts_with('W'))
         return false;
     if (!is_ascii_digit(parts[1].code_unit_at(1)))
         return false;