Creates new page labels that number every page in decimal from 1, replacing any the catalog has.
public PdfPageLabels CreatePageLabels()
ISO 32000-2 §7.7.2, Table 29 (PageLabels, PDF 1.3), and §12.4.2: a new number tree holding the range for page index 0
the clause requires, << /S /D >>. A tree it replaces stays in the file until a save that removes unreachable
objects. A later save of a document below PDF 1.3 raises it to 1.3. A mutation.