Allow scripting tests via CLI

[HalosGhost]

Potentially sensible to tackle at the same time as #5, it would be very useful to enable orchestrating tests from the cli (e.g., might enable larger-scale tests to be executed following a GH workflow). A large part of this is probably easy to accomplish, just about polish of a CLI interface.

However, a slightly larger wish would be to enable an additional environment for #5 to target: local VMs/containers (e.g., KVMs under linux, or virtual box, or just docker containers). Not only does this mean we could leverage a lot of the niceties of the TC's tooling/workflow for local tests, but would enable people to actually test against their own infrastructure seamlessly.