ktest.pl: Allow for the config-bisect.pl output to display to console

When commands are run in ktest, they are only displayed in the ktest log
file, but that is not sufficient for outputting the display for config
bisects. The result of a config bisect is not shown.

Add a way to display the output of "run_command" which is the subroutine
used by ktest to execute commands. Use this feature to display the output of
config-bisect.pl executions to see the progress as well as the result.

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