Standardize/enforce code formatting on the project

[brettcannon]

Prescribed Solution:

• Format all of the extension code
  • Python (using black)
  • js, jsx, ts, tsx, json, css, less, sass (using prettier)
• Format on commit
• Format on save (user settings, opt in using)
  • Use prettier extension
  • Use python extension with black
• Recommend prettier extension in .vscode/extensions.json
  • Use prettier extension
  • Use python extension with black
• Prettier Config settings
  • Prettier rc config (editor agnostic, also picked by CI)
  • .vscode/settings
• CI check for all pipelines (black & prettier)
  • PR pipeline
  • CI Pipeline
• Update contributing guide
• Configure prettier to use tslint (ensure this works on CI)
  • TIP - Look for prettier plugins (plenty good ones)

~Set up [pre-commit](https://pre-commit.com/) and some [hooks](https://pre-commit.com/hooks.html) for anything which runs quickly:~

• Prettier
• Black
• tslint
• pre-commit

.. etc.