python.mk: PEP-517 data_files support

data_files was not initially supported in the framework under the
guise that PyPA through setuptools deprecated the practice. However,
other build backends like flit still support (and advertise as a
"newer" feature) data_files, and certain packages continue to install
operating system-specific files like man pages using Python's
packaging system.

This expands RECORD parsing to account for any data_files beyond
entry_points installed to bin/. It is limited to certain directories
in hier(7) listed under /usr/local to prevent wheels from installing
files to arbitrary locations.

Tested by: yasu (first pass)
Differential Revision: https://reviews.freebsd.org/D38050