fdprogress: add enhanced version of progress_fds written in python

By Alfe (alfe@alfe.de)
progress_fds: re-adopt it for block special devices

But don't use it without explicit pid, since lsof will tell you the
processes that are have opened files from that fs, not processes that
have opened that block dev.
The regression introduced by 247f648f806e93f8e42f6caca6ea7dc381643bea
("progress_fds: show info for all fds by pid")