Workflows should use the same tooling as developers

[glennmusa]

Description

GitHub Actions workflows should use the same Dockerimage that is used for configuring a developer's local environment.

This can be achieved with the jobs.<job id>.container workflow steps: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjob_idcontainer

For now the team could host the image in a private registry, but it should be investigated if there's value in publishing directly to Docker Hub or some other public registry.

Acceptance Criteria

• Where necessary, workflows make use of the container image from the team's private container registry
• A new Service Principal is created with solely "acrpull" scope on solely the private registry resource
• The Service Principal client ID and client secret are stored as encrypted secrets in GitHub
• The Service Principal credentials are stored in some KeyVault with appropriate RBAC permissions