Description of problem:
icmp/icmpv6 rule elements can be omitted when listing ruleset

Version-Release number of selected component (if applicable):
nftables-0.9.8-2.fc34.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Execute the following nft commands:
nft add table ip6 test
nft add chain ip6 test testc
nft add rule ip6 test testc icmpv6 type nd-router-solicit ip6 daddr fe80::/10 drop

2. List the ruleset:
nft list ruleset


Actual results:
table ip6 test {
	chain testc {
		ip6 daddr fe80::/10 drop
	}
}


Expected results:
table ip6 test {
	chain testc {
		icmpv6 type nd-router-solicit ip6 daddr fe80::/10 drop
	}
}


Additional info:
Executing the following:
nft list ruleset >/tmp/ruleset.nft
nft flush ruleset
nft -f /tmp/ruleset.nft

results in the rule not including "icmpv6 type nd-router-solicit". This means that rulesets cannot be saved and restored (to see that the ruleset has not been restored correctly you need a working nft).

This issue is resolved in v0.9.9. nft commit 5335652 resolved the problem, and this can be applied directly to v0.9.8.