Support `--json` mode

I’ve just stumbled upon this package and have to say: it seems super cool!

My company has an internal auditor that runs the appropriate auditors against our repos, and this looks like it could be a complete drop-in that would gain us some very useful features (whitelisting in particular).

However currently audit-ci outputs a few lines of text before & after the JSON audit results - it would be useful if there was a --json flag that would have only the audit results JSON be outputted.

An extension on this could be to then add a auditCi property that contained information from audit-ci, such as what was whitelisted.

I’m happy to work on a PR for this, and have a few ideas on how to go about it - my initial attempt will likely be to just replace all log calls with a logger function call that is a noop if the flag is present.

[quinnturner]

I have not performed any work on this feature at this time. However, I do think it is a valuable addition. I don’t have immediate plans to write this feature myself (may in the future), but I would certainly review PR requests.

[quinnturner]

For further flexibility, I would consider revising the flag from --json to something like --output {none/full/json} (default full). This is slightly different than the --report-type since report-type refers to the output within either a full or json.

I am unsure if this would be a confusing semantic for adopters. Also, since Yarn uses JSON-lines format rather than JSON, that might result in a “gotcha”, but this behaviour can be documented.

EDIT: I am not sure if --output none would ever be the desired behaviour. I made that up on the spot and have never had a request for it.