Convert VPC topology to access mode topology

[auria]

charm-neutron-api-plugin-aci receives raw input via the aci-connection-json parameter. In general, connection information for virtualization hypervisors use:

• a module (vpc--, eg vpc-1-2),
• a port (bundle--1-2-and--1-2, eg. bundle-101-1-2-and-102-1-2) and
• a topology path (topology/pod-1/protpaths--/pathep-[bundle--1-2-and--1-2]).

A common use is to have two switch ports on different Leaf nodes, and form a VPC port channel in LACP mode.

However, other use cases involve setting the same switch ports (on different Leaf nodes) in access mode, and configure an active-backup bond interface on top of them. In this case scenario, I would like to better understand what configuration is supported and that would be needed.

For example:

• module: access-1-2
• port: access-101-1-2
• topology path: topology/pod-1/protpaths-101/pathep-[access-101-1-2]

Please confirm if such configuration is supported by the aimctl manager host-link-update command. If so, I think charm-neutron-api-plugin-aci would also support it as the input shared as Juju configuration parameter is in raw.

Thank you.

PS: A PR has been created to support testing from Ubuntu 20.04 (py38) and an extra test for access mode host links has been created at #302