Setup docker github workflows

[mjpitz]

We should have workflows to build and push the docker images.

On branches, docker images should be built. Since these are largely SDK containers, there isn't much to test about them. When the branch is main, we should push a :latest tag to dockerhub.

[abitrolly]

Done already? https://github.com/depscloud/depscloud/blob/main/.github/workflows/dockerfiles.yaml

[mjpitz]

Different project. This is specifically for the API which has its own set of images used to generate the associated code rather than requiring callers to have the proper protoc environment configured. I could probably move some of this over to using my bin-vendor project, but I think the python install requires libraries and one benefit to the container is that those are encapsulated.