Implement Connection and Virtual Circuit

[displague]

Implement Connection and Virtual Circuit support.

See:

• https://metal.equinix.com/developers/docs/networking/fabric/
• https://metal.equinix.com/developers/api/connections/
• Support for Connection API resource equinixmetal-archive/packngo#234

[displague]

Remove get_packet_connection, create_packet_connection which represent a previous incarnation of the service that is no longer provided.

[displague]

Revise the Changelog for v1.44.0 to create_packet_connection instead of create_connection.