refactor(ui): rewrite file input component

[piprett]

• Rewrite file input component in TS + composition API
• Remove unused props
• Remove frontend duplicate component
• Replace the emit by an async callback
• Add a spinner in the wide display mode while the callback is uploading
  • You should be able to see this in the markdown editor
• Add a red border and error in wide display mode
  • Should be easily testable in the markdown editor
• Make uploading icon the default icon
  • aria-hidden
• Remove fileUtils as it's just checking file size anyways and using alerts
• fmt (webstorm being annoying?)