Introduce pipedream

[mattgauntseo-sentry]

This introduces a new set of GoCD pipelines generated from jsonnet.

1. deploy snuba (a noop pipeline that starts the pipedream flow)
2. deploy snuba US (What is currently snuba-deploy)
3. deploy snuba monitor (Deploys to a single tenant style region)

The main differences from the current snuba.yaml pipeline:

1. The migrate step is now run with approval
2. There were some differences in the canary and prod deploy tasks. Canary had the container dlq-consumer and prod didn't. Production has the container rust-querylog-consumer and canary didn't. I've merged the two steps into one shell script and the label selector for canary vs prod is now managed by an environment variable.

Please let me know if either of the both should be changed some other way.