Build stock babylon optimizer

[maurolacy]

Let's build our own optimizer docker image and push it to docker hub. So that we don't build it every time on CI runs.

This will require a fork of CosmWasm/optimizer (or perhaps, our own tiny babylonlabs-io/optimizer repo), and adding the proper changes to the base Dockerfile; or, maintaining a new Dockerfile-babylon one. Whatever works / it's simpler.

Pushing to docker hub will require a babylon docker user. Perhaps we can push it to Amazon docker registry or so.

[maurolacy]

Here: babylonlabs-io/optimizer#1.