Tools & Test: Add autest to validate `traffic_ctl config` output and also add a new `--default` option.

[brbzull0]

--default option can be used ues alonside with --records to display the default value alonside the current.

This also includes a few test cases to make sure the output generated by traffic_ctl does not break. This should cover what was added by https://github.com/apache/trafficserver/pull/11650

exmaple:

  $ traffic_ctl config match proxy.config.diags.debug --records --default
  records:
    diags:
      debug:
        client_ip: "null"  # default: null
        enabled: 1  # default: 0
        tags: rpc  # default: http|dns
        throttling_interval_msec: 0  # default: 0