Added support for NAT64 when configuring Router NAT

[modular-magician]

Adds sourceSubnetworkIpRangesToNat64 and nat64Subnetwork fields to compute RouterNat, allowing the support for public Router NAT services with NAT64 enabled.

Also adds dns64Config field to dns Policy, allowing the configuration of DNS64 server policies, required when using NAT64.

Fixes: #22116

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compute: added `source_subnetwork_ip_ranges_to_nat64` and `nat64_subnetwork` fields  to `google_compute_router_nat` resource

dns: added `dns64_config` field  to `google_dns_policy` resource

Derived from GoogleCloudPlatform/magic-modules#13522

[github-actions]

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