Add a Makefile for easier local testing of image build during development

It might be worth adding a `Makefile` with some generic targets that would be useful for doing local tests for devs.

Inspect the repository's existing Docker image build files and any documented development workflow first; the issue does not name specific files, targets, or tests. Define the useful local-testing targets from that workflow, and consider the work complete when developers can use the Makefile to run the intended image-build checks locally.

Written by the indexing model from the issue text.