Implement first version

Goals:

• Working macro
• Supports a language parameter
• Supports both inline and standalone

Optional:

• Support all the parameters available in the code macro
• Provide a code macro that replaces the standard XS code macro (to provide better performance without breaking backward compatibility)
• In the future, plug this macro as a code macro implementation, see https://forum.xwiki.org/t/change-the-code-macro-implementation/13308