Implements two new slog.Handlers that attempt to output text in the
same format as existing logrus.TextFormatter implementations. The
most notable differences are that the order of fields in the json
output does NOT match the logrus order and the additional items
in text output are NOT sorted alphabetically like they are in logrus.
Tests added validate the output roughly matches between the two
loggers given the differences noted above. A benchmark test is also
included to demonstrate the improvements slog offers over logrus.
