puppet nftables

Add comments for all the nftable::rules entries

For each nftable::rule this adds an extra concat fragment to
add a comment containing the name and order number for the rule.

The motivation here is to make the mapping from resulting rules back
to puppet code more obvious. When adding a new rule it should be more...

Relax nftables::set::type making it optional

This is needed in case nftables::set is passed raw configuration via
source or content.