rhel8: firewalld-0.8.0 fails to add direct rules when backed by iptables

Issue

firewall-cmd --zone=<zone> --direct --add-rule ipv4 filter <chain> <priority> <args> fails with following error.
```
Error: gen_chain_rules() missing 1 required positional argument: 'transaction'
```
When firewalld is backed with iptables, firewalld's /etc/firewalld/direct.xml may fail to load after upgrading to firewalld-0.8.0.

Red Hat Enterprise Linux (RHEL) 8
package firewalld, affected versions:
- versions after (including) firewalld-0.8.0-2.el8
- versions before (excluding) firewalld-0.8.2-2.el8

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