Cli: enable json output

[CriesofCarrots]

Problem

Some of the cli commands do a lot of client-side processing that make them valuable for users, but the displays are geared toward human eyes only. It is very difficult to ingest this data programmatically.

Summary of Changes

• Add global --output format arg, to set OutputFormat -- currently supports Display (default) and Json
• Implement json output for various process-heavy cli subcommands. All of these subcommands feature ad-hoc printing, so in order to make json serialization easy and data-maintenance sane, collect the data to return in a Cli-specific struct. Then impl Display for the struct to collect/contain human-readable print formatting.
  As a result, once the struct is populated, output format-selection and printing is triggered with a single line:
  OutputFormat.formatted_print(&<STRUCT>);

Fixes #7827

[CriesofCarrots]

@mvines , I would love your feedback on this approach. It's quite a bit of churn, but seems reasonably maintainable, given all the special-case printing going on in the cli.

[codecov]

Codecov Report

Merging #9478 into master will decrease coverage by 0.4%.
The diff coverage is 2.2%.

@@           Coverage Diff            @@
##           master   #9478     +/-   ##
========================================
- Coverage    81.2%   80.7%   -0.5%     
========================================
  Files         277     278      +1     
  Lines       62413   62751    +338     
========================================
+ Hits        50682   50683      +1     
- Misses      11731   12068    +337     

[mvines]

This approach looks great. I like that we'll be able to more easily unit test the business logic of each command now as well.

Probably want to get this landed ASAP to avoid rebase hell. I'd backport to v1.1 to keep us sane through the end of May, but skip the v1.0 backport since that'll only live for another couple weeks

[t-nelson]

Looks great! Should be pretty easy to maintain 🙏

All I've got is a feature request 🙂

Pull request has been modified.