Consider refactoring build-and-run-batch-job to use GitHub webooks to push job state

[dfsnow]

The current Action for submitting Batch jobs to AWS checks the state of the job by periodically polling AWS using its API. This approach works well. However, GitHub Actions jobs are limited to 6 hours of run time, meaning our Batch jobs can only be polled for 6 hours (though they continue to run after the job fails).

I'm confident that a better pattern must exist to handle this than polling, given the commonness of our approach. One alternative I found via a cursory search is using the repository_dispatch trigger. Here's the discussion I found on it.

We should consider doing this in the future, though our current approach works fine for now.