Deployer should submit a summary of the deployability checks.

[tmcgilchrist]

Currently the deployability check just shows as pass or fail, and links to the general project that is being checked.
Often if there are multiple git refs being checked and/or multiple Dockerfiles to check for deployability, it isn't obvious what has failed.

As an improvement ocurrent-deployer should post the summary output of each deployability check with links directly to the failing /passing build step. As per the ocaml-ci compilation UI.