allow agent0 to spin up with an external docker container

[dpaiton]

For checkpoint bot (and possibly lpandarb bot) to get along well with infra, it might be a good idea to give the ability to tell agent0 to not spin up a docker container and instead point to an existing one. Need to investigate & implement the fix if so.

[slundqui]

This was implemented in #1504, but further work needs to be done to fully support and run in infra. This is currently blocked by a release with this implementation: delvtech/hyperdrive#1039

[slundqui]

Fixed with update in infra delvtech/hyperdrive-infra#118