feat: support version/upgrade listing

Closes coop-cloud/organising#130.

pkg/catalogue/catalogue.go

@@ -480,3 +480,23 @@ func GetRecipeVersions(recipeName string) (RecipeVersions, error) {
 
 	return versions, nil
 }
+
+// GetRecipeCatalogueVersions list the recipe versions listed in the recipe catalogue.
+func GetRecipeCatalogueVersions(recipeName string) ([]string, error) {
+	var versions []string
+
+	catl, err := ReadRecipeCatalogue()
+	if err != nil {
+		return versions, err
+	}
+
+	if recipeMeta, exists := catl[recipeName]; exists {
+		for _, versionMeta := range recipeMeta.Versions {
+			for tag := range versionMeta {
+				versions = append(versions, tag)
+			}
+		}
+	}
+
+	return versions, nil
+}