`xcvradm` could use parseable output

[bnaecker]

Many illumos tools support a parseable mode, in which the output is regularly-structured and meant for machine consumption. Rather than nicely-printed tables, output is formatted with a single, often configurable, separator character. xcvradm could benefit from such a mode. Flags to implement include:

• -p or --parseable: select parseable mode, over human-friendly formatting
• -s or --separator: select the separator character
• -o or similar: the list of fields to include in the output. It's also nice to print a list of the available fields, in lieu of a man page.
• -H or --no-header: do not print headers for the selected columns

[rmustacc]

Note you should ensure that -p requires you to pick -o. However, -o can work without -p.

[augustuswm]

@bnaecker @rmustacc We are using xcvrdam in fiber test and output parsing is certainly one of my concerns for it. I'm looking at ipadm as an example to model it off of. Does this track?

[bnaecker]

@augustuswm Yes, that's a good example.