LibUnicode: Add Punycode::decode

Author: https://github.com/skyrising
Commit: 299d35aadc
Pull-request: https://github.com/SerenityOS/serenity/pull/19414
Reviewed-by: https://github.com/AtkinsSJ
Reviewed-by: https://github.com/nico
Reviewed-by: https://github.com/shannonbooth
Reviewed-by: https://github.com/trflynn89

Userland/Libraries/LibUnicode/CMakeLists.txt

@@ -5,6 +5,7 @@ set(SOURCES
     CurrencyCode.cpp
     Emoji.cpp
     Normalize.cpp
+    Punycode.cpp
     Segmentation.cpp
     String.cpp
     UnicodeUtils.cpp