Update Docker job to create containers for tag & use org.opencontainers.image.source annotation

[louise-davies]

Description:
Currently, the docker job runs on pull requests & main & dev branches only, which means we don't have a proper pipeline to create Docker images when we tag a release. As part of addressing this, we should consider adding the org.opencontainers.image.source annotation (see https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file?learn=dependency_version_updates&learnProduct=code-security#docker) - this requires the repo tags matches the docker images tags hence the first part of this issue is a prerequisite.

We should do this for all of our repos, just having the issue in SG to track it generally.

Acceptance criteria:

• Docker images are published to Harbor for tags (corresponding to releases)
• The org.opencontainers.image.source annotation is added to the Docker containers.