Create devcontainer configuration

[schroedk]

As alternative to a conda environment, create a devcontainer.json configuration to use with beyond-jupyter.

Tasks:

• create a Dockerfile based on the existing environment.yml
• create a devcontainer.json in .devcontainer referencing the created Dockerfile
• test the setup with Vscode, run some steps of the refactoring journey

Dev hints:

• consider multistage docker to make the image minimal regarding memory demands
• in thedevcontainer.json you can specify to activate the python plugin inside the devcontainer
• (optionally) if you have the possibility, test the setup with PyCharm, you need access to the Professional version.