CNI plugins may set DNS configuration, but this isn't threaded through to the
task configuration so that we can write it to the `/etc/resolv.conf` file as
needed. Add the `AllocNetworkStatus` to the alloc hook resources so they're
accessible from the taskrunner. Any DNS entries provided by the user will
override these values.
Fixes: https://github.com/hashicorp/nomad/issues/11102