Convert config to *bool

Supports leaving booleans unspecified in YAML.

Boolean methods allow the templates to continue using previous names for
boolean values.

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

internal/app/wwctl/overlay/build/main.go

@@ -71,7 +71,7 @@ func CobraRunE(cmd *cobra.Command, args []string) error {
 
 	}
 
-	if BuildHost && controller.Warewulf.EnableHostOverlay {
+	if BuildHost && controller.Warewulf.EnableHostOverlay() {
 		err := overlay.BuildHostOverlay()
 		if err != nil {
 			return fmt.Errorf("host overlay could not be built: %s", err)