Clean up the docker and lint setup

[haifeng-jin]

• Update the setup for devcontainers (GitHub Codespaces).
  • Use Codespaces official base images for standard setups.
  • Added the required plugins, especially the gh CLI.
  • Enable autoformat on save.
  • Fixed the dependency installs.
• Extract the config of isort and black to pyproject.toml so that the behavior is more consistent when running the commands by different means.
• Change the flake8 to behave consistently in setup.cfg, lint.sh, and format.sh. It use to have 80 char line length in setup.cfg, which would confuse the IDEs. The actual line-length is 200. Ideally, we should just use 80 and comment the long lines with # noqa: E501. If we want this, I can file an issue and call for community help.

[mattdangerw]

LGTM! And nice having you over on the NLP side :)

Just some style nits.

[mattdangerw]

Thank you!