Replace webpack with esbuild

[fjakobs]

What?

1. Replace webpack with eslint as JavaScript bundler
2. Don't use bundled JavaScript during development

Why?

Webpack is slow and hard to configure. Also the npm scripts became a bit messay

Testing

• Created VSIX
  • inspected the contents
  • installed it manually into VSCode
  • tested basic functionality
• Ran all npm tasks
  • test:unit
  • test:integ
  • compile
  • package
  • watch
• Ran extension and extension test from the debug panel
  • made sure that setting breakpoints and debugger works