[new] print/pdfarranger and print/pikepdf

Looking at the py-gtk2 consumers I found py-poppler and pdfshuffler.
pdfshuffler is unmaintained, but it's been forked: enter pdfarranger[0].
It's basically the same tool but with fresher deps and appearance, using
pikepdf[1][2] under the hood.

Feedback & oks to import welcome.