[Feature request] add flag to disable wrapping when using --yaml-output or --yaml-roundtrip

[kindrowboat]

Hello! Thank you for this tool. I've been using it for a while in a few projects. In one of my projects, I am emailing and SMSing the resulting YAML (I know, a little weird,) and so the word wrapping can look off, especially if the recipient is using a non-fix-width. I know you can set --width to be arbitrarily large, but to me that feels a little clunky. Would you consider adding a flag, (e.g. --no-width or --no-wrap) to disable the wraping?

If you're OK with adding that flag, I'd be happy to submit a PR.

[kislyuk]

This sounds good to me. I think I'd prefer to have --width 0 to trigger this. Please open a PR.