define a story for compiling and packaging the user function

[marcellanz]

• users might like to compile the user function within a defined and non-changing environment, like a docker container.
• depending on the users environment, it could be challenging to have the right tools/compilers and dependencies installed. experts are willing and eager to have it, but others might like to get a bit help.
• can be https://code.visualstudio.com/docs/remote/containers used?

see the existing travis-ci build configuration where we build already in a docker container.