fdo#79591 Values for docPr name and shape ID attributes were set invalid

Values set for docPr name and shape ID attributes in RT file were not valid
as per UTF-8 encoding format and hence was showing RT document as corrupt with
error message "invalid character".

Calling add() function with current parameters is causing issue and
setting invalid values so modified the second parameter which will
set valid values to the specified parameters.

Reviewed on:
	https://gerrit.libreoffice.org/9746

Change-Id: I3b48e53adbe5ed844235e596bb98eb396133845a