Remove kernel from runme.yaml and add explicit docker support

[adambabik]

This change removes complicated kernels and introduces an explicit support for Docker:

docker:
  enabled: true
  image: runme-runtime:latest
  build:
    context: ./experimental/docker
    dockerfile: Dockerfile

Running code blocks in Docker is still not fully implemented.

[sonarcloud[bot]]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
72.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud