XML Escape/Unescape Functions

In order to facilitate interaction with XML based data sources (for example, REST endpoints returning XML data), it would be beneficial for TDV to have built-in functions for escaping, and unescaping, XML data.  Currently, there is no functionality in TDV to perform either of these operations in a controlled fashion. 

Please implement the following XML manipulation functions into TDV:

• xml-encode({any valid datatype that can be converted to a VARCHAR}) – escape the input argument so that it’s contents are not evaluated as XML data, following the standards for escaping parser tokens in an XML document.
  
  
• xml-decode({any valid datatype that can be converted to XML}) – the inverse of the above – convert an escaped value (as in xml-encode) into an XML fragment, causing TDV to treat the returned value as an XML data type, and handle it accordingly (i.e, if used in a transform, the value should be treated as XML, and evaluated as such)

Currently, being unable to use this kind of functionality within TDV requires complicated workarounds to support more advanced XML based workflows.  (e.g, writing Custom Java Procedures, or using less advanced kinds of TDV functionality (using a Tabular transformation, instead of an Any-to-Any transformation)).