Refactor otter grade image builds so that assignment data is not included in the grading image about otter-grader HOT 1 OPEN

I think this is a really good idea. It should be possible to do a refactor like this; the main thing is that the new logic would need to make sure that it rebuilds the "base" image if the autograder zip has different requirements. To achieve, this it should be relatively easy to create two images in otter grade, one with only the requirements that's tagged with a hash of the environment.yml file from the autograder zip file, and a second built on top of that image with the tests and configurations loaded in. When otter grade runs, it can hash the environment.yml file, check whether an image with that tag exists, and then it won't need to rebuild the image.

If you'd like to contribute this refactor, I'm happy to review any PRs.

from otter-grader.