Add vscode support for DataHub

[czgu]

Story As a user, I want to use Vscode to develop DataHub with minimal amount of effort

Acceptance

• Suggest a list of extensions that are essential for DataHub development (prettier, black, etc)
• Suggest some standard vscode settings (formatting on save etc...)
• Make devcontainer.json so that users can easily launch datahub with vscode

[jczhong84]

for the last one of using dev container, it doesn't support of connecting multiple containers in a single window. Although there are workaround, it wont make things easier.
https://code.visualstudio.com/remote/advancedcontainers/connect-multiple-containers