Ensure that editor config is created properly

[danmaninc]

• [x] Prettier and ESLint installed
  • In other words, defined in .idea
• [x] Editor configuration (.idea) should include:
  • [x] Format on save enabled
  • [x] Default formatter configured to Prettier
  • [x] ESLint configured to auto-fix all auto-fixable problems
• [x] The editor configuration should be version controlled and used by all team members.
  • i.e., the .idea folder is not gitignored

If not all team members use VS Code, then the equivalent EditorConfig settings should be used.