feature request: ignore specific lines instead of entire file

I would like to mark a line as to be ignored by yamlfmt. Similar to the use of `# noqa` and similar ignore syntaxes.

I'm using yamlfmt to format CircleCI config files, which references variables as `<< foo.bar >>` and this should not be reformatted. But when limiting line length to N, yamlfmt will try to break it down in smaller lines.