[Feature Requests] Publish pre-built docker containers to a public repo

As a user I would like to not have to work through the steps to build a docker container for use. One should be readily available. It would also alleviate build issues based on machine as see in PR #8.

Pushing to the public ECR repo seems like a logic choice since this is an AWS project but pushing to DockerHub could work as well. Would effectively make this comment and running in Github less headache if every end user of LZA didn't have to build the same image. https://github.com/aws-samples/lza-validator/issues/7#issuecomment-2167207127

But also makes implementing #7 request easier as well since github actions can just be a layer on top of that docker container. https://docs.github.com/en/actions/creating-actions/creating-a-docker-container-action

Review PR #8 for the reported container build issues and issue #7 for the related GitHub Actions request. Compare publishing to AWS ECR versus DockerHub, then define the container publishing workflow and verify that users can pull a public image instead of building locally.

Written by the indexing model from the issue text.