local test-composer

[carlsverre]

new snouty subcommand which when pointed at a docker compose file, simulates what the test composer does:

1. spins up the docker compose environment, injecting antithesis sdk path env variable and supporting post-start
2. search for antithesis test composer entry points
3. monitor for the setup event
4. fuzz the entry points
5. loop on 1

It's obviously not going to actually catch real bugs, but it will serve as a fast way to verify the antithesis test environment is mostly correct.