NoirRunner

Everything this scan did not cover, from any phase. Empty is the positive statement "the scan read what it was pointed at and delivered what it was asked to", which is what tells a degraded scan from a clean one — and what --strict exits 2 on.

Renders the diff in the requested format and returns it, so the caller can apply --fail-on to the same result instead of computing it twice.

Renders the report in the requested format. Which builder that is, and which formats exist at all, is the annotated-builder catalog's business (Noir::OutputFormats) — this used to be a 70-line case that was the fourth place a format had to be listed.