Add `--color` flag

[rgoldberg]

New Issue Checklist

• I've Updated SwiftLint to the latest version.
• I've searched for existing GitHub issues.

Feature or Enhancement Proposal

Please add a --color flag that keeps output colored regardless of pipes, etc.

[SimplyDanny]

As far as I know, there is no colorized output at all. We'd rather have to introduce that in the first place. Or what does this relate to?

[rgoldberg]

Oops. I meant to submit this feature request to SwiftFormat. 🤦‍♂️