Reverse companion to as_tibble.pdfium_annot_list(): takes
either an existing list of pdfium_annot handles or a tibble
produced by as_tibble() and returns a pdfium_annot_list.
Reverse companion to as_tibble.pdfium_annot_list(): takes
either an existing list of pdfium_annot handles or a tibble
produced by as_tibble() and returns a pdfium_annot_list.