Development docker-compose.yml and Dockerfile

[khiron]

Run in a local path containing a clone of your fork of the cogent3 repo

• python version pinned
• pip install cogent3 requirements.txt
• copy cogent3 clone
• add .git pre-commit hooks
• black
• isort
• prod node with a bash entry point
• test node with a pytest entry point
• debug node using ptvsd with a pytest entry point
• ensure security keys allow the project to be checked in from the container