Package formfill provides support for filling forms found
in PDF files (aka AcroForm), reading forms input
either form an FDF file or directly from memory.
FillForm fill the AcroForm contained in the document
using the value in `fdf`.
If `lockForm` is true, all the fields are set ReadOnly (even the ones not filled).
See FillFormFromFDF to use a FDF file as value input.