bib: add support for ID_LIKE when finding the distro YAML

This commit adds a fallback check when no direct match for
the distro ID from the bootc image is found. As long as
the bootc container sets a correct `ID_LIKE` we should
automatically have the same behavior as before when
we used symlinks as aliases.

If needed we might need to reintroduce an explicit
mapping like:
```go
// mapping of distro IDs that are compatible with
var distroCompat = map[string]string{
	"almalinux":     "rhel",
	"aurora":        "fedora",
	"aurora-helium": "rhel",
	"bazzite":       "fedora",
	"bluefin":       "fedora",
	"heliumos":      "rhel",
	"rocky":         "rhel",
}
```
but lets hope we don't need this.

Author: mvo5

bib/cmd/bootc-image-builder/legacy_iso.go

@@ -222,22 +222,40 @@ func labelForISO(os *osinfo.OSRelease, arch *arch.Arch) string {
 	}
 }
 
+// newDistroYAMLFrom() returns the distroYAML for the given sourceInfo,
+// if no direct match can be found it will it will use the variantID.
+// This should ensure we work on every bootc image that puts a correct
+// ID_LIKE= in /etc/os-release
+func newDistroYAMLFrom(sourceInfo *osinfo.Info) (*defs.DistroYAML, *distro.ID, error) {
+	for _, distroID := range []string{
+		sourceInfo.OSRelease.ID,
+		sourceInfo.OSRelease.VariantID,
+	} {
+		nameVer := fmt.Sprintf("%s-%s", distroID, sourceInfo.OSRelease.VersionID)
+		id, err := distro.ParseID(nameVer)
+		if err != nil {
+			return nil, nil, err
+		}
+		distroYAML, err := defs.NewDistroYAML(nameVer)
+		if err != nil {
+			return nil, nil, err
+		}
+		if distroYAML != nil {
+			return distroYAML, id, nil
+		}
+	}
+	return nil, nil, fmt.Errorf("cannot load distro definitions for %s-%s or %s-%s", sourceInfo.OSRelease.ID, sourceInfo.OSRelease.VersionID, sourceInfo.OSRelease.VariantID, sourceInfo.OSRelease.VersionID)
+}
+
 func manifestForISO(c *ManifestConfig, rng *rand.Rand) (*manifest.Manifest, error) {
 	if c.Imgref == "" {
 		return nil, fmt.Errorf("pipeline: no base image defined")
 	}
-
-	nameVer := fmt.Sprintf("%s-%s", c.SourceInfo.OSRelease.ID, c.SourceInfo.OSRelease.VersionID)
-	id, err := distro.ParseID(nameVer)
-	if err != nil {
-		return nil, err
-	}
-	// XXX: ensure all aliases we have for bib are available in
-	// images
-	distroYAML, err := defs.NewDistroYAML(nameVer)
+	distroYAML, id, err := newDistroYAMLFrom(c.SourceInfo)
 	if err != nil {
 		return nil, err
 	}
+
 	// XXX: or "bootc-legacy-installer"?
 	installerImgTypeName := "bootc-rpm-installer"
 	imgType, ok := distroYAML.ImageTypes()[installerImgTypeName]