Carry the catalogue's predefined.json with a build, and declare the config verb (hq issue 630)

The controller only learns manifests through builds, so the list of predefined keys travels the same way: the builder reads it at the catalogue's root, judges the manifest against it and hands it on.

cmd/mesh-builder/main.go

@@ -327,6 +327,7 @@ func answer(ctx context.Context, publisher builder.Publisher, on, workspace stri
 			}
 			result.Against = built.Against
 			result.SourceFingerprint = built.Source
+			result.Predefined = built.Predefined
 			result.Trunk, result.OnTrunk, result.Branches = built.Trunk, built.OnTrunk, built.Branches
 			for _, r := range built.Read {
 				result.Read = append(result.Read, link.ReadRepository{Repository: r.Repository, Ref: r.Ref})