traffic_ctl: Display YAML format when --records option is set (instead of the legacy records.config style)

[brbzull0]

This PR changes the traffic_ctl config output when --records is requested.
--records was used to display the output of a record in the records.config configuration style:

$ traffic_ctl config get  proxy.config.diags.show_location proxy.config.diags.logfile_perm proxy.config.diags.logfile.filename --records

CONFIG proxy.config.diags.show_location INT 2
CONFIG proxy.config.diags.logfile_perm STRING rw-r--r--
CONFIG proxy.config.diags.logfile.filename STRING diags.log

As we do not support records.config style anymore, it now make sense to have just YAML, so the same command will now display:

$ traffic_ctl config get  proxy.config.diags.show_location proxy.config.diags.logfile_perm proxy.config.diags.logfile.filename --records
records:
  diags:
    logfile:
      filename: diags.log
    logfile_perm: rw-r--r--
    show_location: 2

For things like traffic_ctl config diff --records it will add the default value as standard YAML comment.

Note: This is the main reason why this PR uses YAML::Emitter and not just the YAML::Node to build up the yaml doc, it would have been very easy just to use the YAML::Node but it cannot keep track of the comments which for things like the diff option is key.

$ traffic_ctl config diff --records
records:
  diags:
    debug:
      tags: quic|udp  # default: http|dns
    show_location: 2  # default: 1
  http:
    server_ports: 8080 4443:ssl 4443:quic  # default: 8080 8080:ipv6
  quic:
    initial_max_streams_bidi_in: 5  # default: 100
    initial_max_streams_bidi_out: 100000  # default: 100
  udp:
    enable_gso: 0  # default: 1
    threads: 1  # default: 0

if no --records option is passed, the behavior remain unchanged.

fixes: #11607

[brbzull0]

Will fix CI: Fixed

../src/traffic_ctl/PrintUtils.h:85:1: error: 'const char* rec_sourceof(int)' defined but not used [-Werror=unused-function]
   85 | rec_sourceof(int rec_source)
      | ^~~~~~~~~~~~
../src/traffic_ctl/PrintUtils.h:73:1: error: 'const char* rec_labelof(int)' defined but not used [-Werror=unused-function]
   73 | rec_labelof(int rec_class)
      | ^~~~~~~~~~~
../src/traffic_ctl/PrintUtils.h:42:1: error: 'const char* rec_updateof(int)' defined but not used [-Werror=unused-function]
   42 | rec_updateof(int rec_updatetype)
      | ^~~~~~~~~~~~
../src/traffic_ctl/PrintUtils.h:29:1: error: 'const char* rec_accessof(int)' defined but not used [-Werror=unused-function]
   29 | rec_accessof(int rec_access)

[cmcfarlen]

Worth adding a test or two?

[brbzull0]

Worth adding a test or two?

definitely yes. I'll add them.
Thanks Chris.

[brbzull0]

Worth adding a test or two?

@cmcfarlen : done -> #11740