ph-ubl 6.2.1

• Added predefined constants for shared XSDs in the CUBL.. classes
• Fixed a classloader issue in ph-ublpe in OSGI environments
• Started new subproject ph-ubl-dian for the Colombian eInvoice
  • Based on https://www.dian.gov.co/fizcalizacioncontrol/herramienconsulta/FacturaElectronica/Documents/Caja_de_herramientas_Factura_Electronica_Validacion_Previa.zip
• Updated to UBL 2.3 CSPRD02