Include nftables information in Agent supportbundle

[hongliangl]

Antrea introduced nftables for some features. The supportbundle currently doesn't include nftables rules.

Reference:

antrea/pkg/support/dump_others.go

Lines 50 to 60 in 4e74a6b

	func (d *agentDumper) dumpIPTables(basedir string) error {
	c, err := iptables.New(d.v4Enabled, d.v6Enabled)
	if err != nil {
	return err
	}
	data, err := c.Save()
	if err != nil {
	return err
	}
	return writeFile(d.fs, filepath.Join(basedir, "iptables"), "iptables", data)
	}

Only table ip antrea and table ip6 antrea should be included because these two tables are managed by Antrea.

root@kind-control-plane:/# nft list tables
table ip nat
table ip mangle
table ip filter
table ip6 mangle
table ip6 nat
table ip6 filter
table ip raw
table ip6 raw
table ip antrea
table ip6 antrea
table ip kube-proxy
table ip6 kube-proxy

[molegit9]

Hi, this looks like a good first issue. I would like to work on this. Could you please assign it to me? Thank you!

[ADITYATIWARI342005]

Hi @molegit9
Your PR seems to be failing in workflow, also you forgot to sign-off the commit, use git commit -s -m "message" from next time.
For now, do git commit --amend and then force push the changes.
For the failing workflow/CI checks, debug the code and check logs...It needs to be fixed for merging the PR.