feat: Add production like docker compose for docs

[AshtonStephens]

Description

Closes: #785

Note: This is NOT meant to be run! It is solely for documentation, but is close to accurate!

This PR creates a docker compose and configuration files meant to be used solely in documentation. The primary goal is
to give those who will be running signers the right idea of what will be required. This docker compose calls upon docker
images that aren't published yet.

I fully expect us to need to make decent changes to these, but the communication aspect won't be greatly changed by
the changes we'll need to make.

I've opted to leave in some of the TODO(123) comments in the signer configuration because I think leaving them in
makes it clearer what work needs to be done and what they can expect will have changes before they deploy.

Changes

Adds three files:

docker/prodlike
├── config
│   ├── blocklist-client-config.toml
│   └── signer-config.toml
└── docker-compose.prod.yml

Testing Information

Not tested.

Checklist:

• I have performed a self-review of my code
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[cylewitruk]

Just a little note that this doesn't reduce the final image size as it's still included in a previous layer, unless the image is built with --squash.

[cylewitruk]

You know, I thought I had removed this a while back -- anyone know how/why it's popped back up?

[cylewitruk]

I don't think we need the SIGNER_ env-vars here. This was a solution in devenv to use the config file as a base, but these needed to be different for each signer instance. For this example I think everything can just be pulled from the config.

[djordon]

We should update this to 16.3, which is what we test against.