[BUG] firewalld.service fails due to missing modules

WALA invokes a few firewall rules which depend on certain kernel modules. e.g. "-m owner" and "-m conntrack" rely on xt_owner and xt_conntrack. These modules reside in kernel-modules-extra package for distros like RHEL.
Because kernel-modules-extra is not a dependency of iptables or firewalld, these rules can fail.
Culprit: https://github.com/Azure/WALinuxAgent/blob/master/azurelinuxagent/ga/firewall_manager.py#L377

This is not an issue previously because kernel package pulls in kernel-modules-extra with kernel-modules-extra-matched which is a dependency of iptables. Unfortunately this is not the case in term of UKI.

Example failure messages:
```
firewalld[8037]:
ERROR: COMMAND_FAILED: Direct: '/usr/sbin/iptables-restore -w -n' failed: Warning: Extension tcp revision 0 not supported, missing kernel module?
Warning: Extension owner revision 0 not supported, missing kernel module?
Warning: Extension conntrack revision 0 not supported, missing kernel module?
iptables-restore v1.8.11 (nf_tables):
line 3: RULE_APPEND failed (No such file or directory): rule in chain OUTPUT
line 4: RULE_APPEND failed (No such file or directory): rule in chain OUTPUT
```

Therefore, WALA should add some checks/fallbacks when these kernel modules don't exist.