make stack traces tool find individual traces

previously the tool just reprinted out TRACE and ERROR log lines.
Now make it actually collect up TRACE and ERROR into individual
events which will make it easier to cross reference to tempest
tests.

built additional features around stack trace tooling, making it
simpler to find unique events.

Change-Id: Id1fed3343e79e75da3145b5a9c19820b65a0d548
1 file changed