Publish container image to quay.io/azavea account

In order to save users the step of having to build the image locally.

Not pressing, as build times aren't long, but a nice to have at some point.

The issue names no files, tests, or entry points. Start by locating the repository's Docker image definition and any existing build or release workflow, then determine how an image can be published to the quay.io/azavea account; done means users can pull the published image instead of building it locally.

Written by the indexing model from the issue text.