convertToString() Operation for DateTime Objects

Syntax	NONE `set aString = aDateTime.convertToString();`
Semantics	`convertToString()` returns the internal lexical representation of DateTime (`"CCYY-MM-DDThh:mm:ss[.sss][Z\|[+\|-]hh:mm]"`) as String.
Substitutables	`aDateTime`	Can be any variable or object attribute having the type DateTime.
Examples	NONE `set aDateTimeString = aDateTime.convertToString();`