Investigate integration with Clipboard API

[tim-evans]

Investigate hooking into paste events in browsers and allowing users to disable this feature if they would like to.

See https://developer.mozilla.org/en-US/docs/Web/API/ClipboardEvent

[jelhan]

I'm not sure how this is expected to work:

• What would be the expected and supported ClipboardEvent.clipboardData? I think it must be a File or a Blob cause reading a file from disk by provided path is not supported in Browser due to security concerns as far as I know.
• What element should listen for the paste event? The dropzone and file input? This would mean that the user must first focus them before pasting. Not sure if that's an intuitive user experience.
• Is there any default behavior if a user pastes to a file input?

A proof of concept would be great before starting actual implementation. Just in case someone wants to pick this one up. 😄

[gilest]

Had a look on MDN:

• Can listen for a paste event on window, document, or element (for good UX I think window/document listening makes sense)
• Paste event is a ClipboardEvent
• ClipboardEvent has clipboardData property which is a DataTransfer object
• DataTransfer has getAsFile which returns an HTML5 File object

What should the API for this be though?

Perhaps configurable on the helper/service and disabled by default

Would be worth bundling a feature like this in with major changes like in #316 to reduce API churn