feat: Containerfile to create image from current source

[Blaimi]

PR summary

This PR adds a Containerfile to the repository and documentation on how to use it.

Documentation about container images have been removed in #599. Because of this, the image at jamescooke/openapi-validator got marked as deprecated.

PR Checklist

General checklist

Please make sure that your PR fulfills the following requirements:

• The commit message follows the Angular Commit Message Guidelines.
• Tests for the changes have been added (for bug fixes / features)
  • I made a github workflow which builds and uploads the image (build-image.yml), the build part could be adapted to test the build on every push/pr. Adapting the upload task would require some decisions about the image-target (dockerhub, quay, …) and how to handle tags and autobuilds.
• Docs have been added / updated (for bug fixes / features)
• Dependencies have been updated as needed
• .secrets.baseline updated as needed?

[JohnStarich]

@dpopp07 Thoughts on closing this one as complete since it was merged as part of #620?

[dpopp07]

@JohnStarich good call

@Blaimi thanks for your effort on this!