Clean the docker runtime

[ferranbt]

This PR cleans a few things on the docker runtime:

• It moves the application of the overrides (user can override which images/binaries use during execution) out of the runtime since they only modify the manifest (here).
• Fixes the component unit tests. The way it was done before, the inputs were not modified since the test framework would apply the default variables. (here).
• Moved the logic for the interactive mode out of the docker runtime using the callback interface from Pull images in playground itself instead of docker-compose to have visibility on pull actions #232 (here). It does not make sense that the Docker runtime owns the component that deals with the visualization on the terminal.