Function write_apply_artifacts 

pub fn write_apply_artifacts<W: ArtifactWriter>(
    apply: &BuildfixApply,
    report: &BuildfixReport,
    patch: &str,
    out_dir: &Utf8Path,
    writer: &W,
) -> Result<()>

Emit all apply artifacts (apply.json, apply.md, patch, report, extras).