*(dhcpd): refactoring, use dhcpd/network_utils where possible

dhcpd/network_utils_darwin.go

@@ -0,0 +1,8 @@
+package dhcpd
+
+// Check if network interface has a static IP configured
+// Supports: Raspbian.
+func hasStaticIPDarwin(ifaceName string) (bool, error) {
+
+	return false, nil
+}