Ability to list codeowners

[paularmstrong]

Given any of the following:

• The current set of modified files
• An input file or files
• An input Workspace or Workspaces

I would like to see who the codeowners are in a readable format. This could help with understanding who or whom I should reach out to with questions, or whom I can expect will need to review a PR.

The main question here is how the output should be formatted.

one codeowners show
one codeowners show --format=plain

But what does this output look like?

• Should it use cliui and build a table output like we do for one graph show --format=plain
• Should it just be a simple list of ${filepath}: ${owners.join(', ')}?

Also there's never a reason to not have an optional JSON format output.

one codeowners show --format=json