Currently, we are running `arc lint --everything --never-apply-patches --output=xml > checkstyle.xml` in Jenkins, The output redirection is a little odd and not inline with other scripts that we run in CI. I think that it would be useful to be able to send the output from Arcanist to a file for this purpose. This might not be useful outside of lint/unit, so possibly it could be implied that adding `--output=xml` will write the results to `checkstyle.xml`.