Recommended refactors

- make sure spec sets new cache dir
- move clean out of api
- capture warewulfconf.Paths.Cachedir+"/warewulf" in once place
- split Clean() into multiple functions
- remove WriteFileAbs

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/app/wwctl/clean/main.go

@@ -1,13 +1,19 @@
 package clean
 
 import (
-	"github.com/warewulf/warewulf/internal/pkg/api/clean"
+	"github.com/warewulf/warewulf/internal/pkg/clean"
 
 	"github.com/spf13/cobra"
 )
 
 func CobraRunE(vars *variables) func(cmd *cobra.Command, args []string) (err error) {
 	return func(cmd *cobra.Command, args []string) (err error) {
-		return clean.Clean()
+		if err = clean.CleanOciBlobCacheDir(); err != nil {
+			return err
+		} else if err = clean.CleanOverlays(); err != nil {
+			return err
+		} else {
+			return nil
+		}
 	}
 }