hcloud_inventory: Optimize --list to avoid --host calls
By adding a top-level element called "_meta" to the --list response, Ansible will not call the inventory script with --host for each host thus saving a lot of time and many requests to the Hetzner Cloud API.
The speed-up is significant; ansible-inventory --list
is down from
about 1 minute to just 7 seconds in my testing (with ~60ms latency).