Consider docker for running tests

[nettle]

Describe the task

We may use docker (Dockerfile) for multiple purposes, for instance:

• run tests in "clear" environment
• run tests in different environments, different tool versions etc
• reveal hidden dependencies

Scope

1. Develop Dockerfile(s) with "empty" (no preinstalled packages) images
2. Reveal hidden requirements and describe them
3. Consider using Dockerfile(s) for testing
4. Consider adding as .ci/docker/Dockerfile

Definition of Done

• Docker usage is considered and prototyped
• Hidden dependencies revealed
• Discussed the possibility to use docker for testing
• New tickets created to follow-up