iotedgehubdev should be a self-contained docker container

iotedgehubdev currently requires the user to install Python no matter their development language, which can cause unnecessary friction; particularly since iotedgehubdev requires a specific, older version of Python (<3.8).

Many OSs package more recent versions of Python, requiring the user to take special action to parallel install or downgrade their installations. On Windows, the Python.org homepage doesn't even offer binaries for the latest Python 3.7.10 release which is a security fix.

iotedgedev should be packaged up as a Docker container which can run docker-in-docker or simply pass through commands to the host's Docker socket.