Inserts an existing page object of the document, not yet in the page tree, at index.
public PdfPage Insert(int index, CosReference pageObject)
The page object's reference: a dictionary added with AddObject(CosObject), for instance a page copied from
another document. Its Type shall be Page (it is set when absent).
ISO 32000-2 §7.7.3.2 and §7.7.3.3 (PDF 1.0). A page appears in the page tree once, so a page of the document is moved with
Move(Int32, Int32), not inserted again. The page's Parent is set; the attributes it does not have are not inherited
from anywhere, so give it its own MediaBox and Resources.