Add support for Equinix Metal Metros

[displague]

Equinix Metal facilities can now be treated as aggregate, in many ways, using metros:

• https://feedback.equinixmetal.com/changelog/new-metros-feature-live

TODO

(add more or sub-levels as needed)

• Introduce a new metro_info module
• Introduce Metro features where applicable (info, inventory, and managing modules):
  • Facilities (now include a metro field)
  • Plans (now include available_in_metros)
  • Capacity Info (now has a separate /capacity/metros GET/POST endpoint)
  • Devices (now include a metro field)
  • VLANs (may include a metro field)
  • (N/A, not implemented in Ansible) Hardware Reservation, Batch, SpotMarket, SpotMarketPrices
  • (N/A, not implemented in packet-python) Connections (Implement Connection and Virtual Circuit packethost/packet-python#111), IP reservations (Implement IP Reservation handling packethost/packet-python#109)
  • (N/A, not metro-enabled) Volumes (also not in Ansible)

When provisioning these resources, either a facility or a metro parameter should be provided.

Device and IP Address responses, for existing resources, will return both facility and metro responses.
VLAN resources will only return a metro or facility (along with metro_code, facility_code) depending on how they were provisioned.

Depends on packethost/packet-python#108

[dlotterman]

Just commenting for the transcript that the Facility / Metro handling in the IP reservations context (cited above or here) is currently causing flakey user behavior.

I'll try to capture the notes to reproduce / document shortly.