Slides: Modify Underlying Xml

Directly eidt the underlying xml of a Slide object within an OpenOpenXml (e.g. Excel, Powerpoint) document. This endpoint will validatate the submitted xml against the Ecma-376 standard prior to saving modification. Invalid xml will rejected by this endpoint and a (hopefully) helpful error message will be returned. Use this endpoint for client-side automation of modifications ot Slide objects.