build(dockerfile): update dockerfile to handle deploying to production

[chrispymm]

Amend dockerfile to be multistage and allow generating a different image for staging and production. Production needs to be different as it needs to not have http auth, not have the staging banner, and it needs to be built from a git repo to eanble the 'last updated' functionality for components.

[github-actions[bot]]

🚀 Deploying to staging environment

Username: staging, Password: moj

[gregtyler]

:tada: This PR is included in version 2.2.1 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: