ktest.pl: Have config-bisect save each config used in the bisect

When performing a automatic config bisect via ktest.pl, it is very useful to
have a copy of each of the bisects used. This way, if a bisect were to go
wrong, it is possible to retrace the steps and continue at the location
before the error was made.

The ktest.pl will make a copy of the good and bad configs, labeled as such,
as well as a number attached to it that represents the iteration of the
bisect. These files are saved in the ktest temp directory where it currently
stores the good and bad config files.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>