When forward dns request to outside name server, `aardvark-dns` should check and ignore its own listening IPs or error out, to avoid infinite recursion.

[xiaoyar]

aardvark-dns should be improved as the title mentioned, more details can be found here: containers/netavark#855.

[xiaoyar]

Another improvement we can expect is to make sure the name servers in dns_resolver to be unique, otherwise if a name server fails to resolve and it duplicates in the list, it may be tried more than once, that's bad for performance.