Consider a true pretty-printed JSON format type

We currently have three JSON output formats:

- `json`: which gives you proper JSON output
- `json-lines`: which gives https://jsonlines.org/ formatted lines, great for streaming
- `json-pretty`: which gives you `json-lines` except with colors and some CLI friendly formatting if you're in a terminal

What we don't have is an output format that will output an easy-to-read, formatted JSON file similar to what you'd get from `JSON.stringify(result, null, INDENT_SIZE);` or running the `json` output through something like Prettier, that is actually valid JSON. Mostly, I think this is what people would expect from the term `json-pretty`.