Create a local test environment for Conjure client, relay station, and bridge

We're going to have to work with Eric and the refraction networking relay station maintainers to deploy connect the various Conjure pieces we need. Ideally we'd set up a test environment to try out different details and designs first so we're not just testing everything in production.

I've done a Docker-based setup for testing refraction networking (a.k.a decoy routing) before with the Slitheen test-env. Something similar might be repurposed here.