Centralize format handling

[eaton]

In a number of places, we pull in JSON files for configuration. proload supports YAML and JSONC, however, and for our config files those are often much nicer. Even JSONC is a bit of a clonk, though, and in places where we're outputting config information we still only support JSON.

• [x] Add json5 and js-yaml dependencies
• [x] Write a register plugin for Preload to support JSON5 files (see the jsonc plugin as an example)
• [ ] When updating our CLI tools, where appropriate, use a --format flag that allows json, json5, and yaml values.

[eaton]

The 0.10.0 reporting infrastructure eliminates most of the need for CLI driven output format settings. Calling this one closed!