Description

Fix the Dockerfile and add the Docker build to the CI.
The docker build error was:

1.359 E: Failed to fetch http://security.debian.org/debian-security/dists/stretch/updates/main/binary-amd64/Packages  404  Not Found
1.359 E: Failed to fetch http://deb.debian.org/debian/dists/stretch/main/binary-amd64/Packages  404  Not Found
1.359 E: Failed to fetch http://deb.debian.org/debian/dists/stretch-updates/main/binary-amd64/Packages  404  Not Found
1.359 E: Some index files failed to download. They have been ignored, or old ones used instead.

Also use a minimal image for the final build stage. New image size is 240MB vs 4.4G for the old one.

In a follow up PR we could add multi-arch build support and automatic image upload to Docker registries.

Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• included the necessary unit and integration tests
• reviewed "Files changed" and left comments if necessary

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)