added devcontainer support for vscode

[akyriako]

Added Dev Container support to automate the lifecycle of local development setup using VSCode and containers. Based on the existing Dockerfile (copied under the new .devcontainer folder) the following VSCode extensions were added:

• Python, Python Debugger, Pylance (Microsoft extensions)
• Git Graph (mhutchie.git-graph)
• Resource Monitor (mutantdino.resourcemonitor)
• Diagrams Previewer (tehpeng.diagramspreviewer)

The new .devcontainer/Dockerfile additionally installs the following packages in base image:

• nodejs
• npm

!! The docker/dev/Dockerfile is no longer needed but it's been left intact. !!