Office Importer: Keep Chapter Ordering When Splitting Imported Documents by Headings

Utilize XWIKI-16453 in the Office document importer.

Copied from there:

The Office document importer feature with enabled "split document" option also generates more or less confusing / mixed-up results, depending on how the headlines are actually formatted in the imported document.

As an office text document is linear / sequential by nature, a result where the imported chapters swap positions (or you get a more or less random permutation of the original chapter / section order) is most definitely not what is needed.

Currently a work around is to tweak the headline formatting before import such that one gets the expected result.

It would be easier, though, if the Office importer could also just use the page / space ordering feature in order to stick all generated pages / spaces to their original position, relative to each other.