Merge branch '2022-08-05-buildman-integrate-boardscfg'

To quote Simon:
This series drops the need for the genboardscfg.py script, so that the
boards.cfg file is produced (and consumed) entirely within buildman. The
file is not entirely removed since it does have some uses and we need some
sort of cache for the information. The genboardscfg.py script is
effectively incorporated in buildman.

It also improves operation from an IDE with a new -I option and fixes up
some of the pylint warnings in buildman.

Finally, this series also fixes a bug which allows use to drop support for
CONFIG_SYS_EXTRA_OPTIONS which is long-standing desire. It also fixes a
minor bug that causes 'Invalid line' spam when checking for function bloat
with the -B option.