Allow getOoxml to return a part of the table when only limited rows are within content control.

This is a feature request appearing as a result of this discussion https://github.com/OfficeDev/office-js/issues/6350

Basically, as I was informed, the default behavior of getOoxml function of API is to return full table markup around the rows if only a limited number of them are wrapped with content control. There is no way right now to get a clean, unedited xml of content control that wraps some portion of table rows (aka table body). No other specific function for it, neither getOoxml overload or additional parameter, which would allow the user to control it.

I am requesting to include an option to retrieve clean xml markup ('unsafe' maybe), not just a standalone table.