Feature Request: Button for selecting File for input

[masq]

Summary

Right now, in order to import a file as input to CyberChef, you must drag and drop a file into the input box. This is pretty handy at times! However, it's:

• Not clear to users that that's available as an option, and
• Sometimes not user-friendly, particularly when one doesn't have a traditional Window Manager, for example if using i3wm.
  It would be nice if there were a button along the input box that upon clicking would prompt a user to select a file (or files?) from their filesystem that they would like to import as input to CyberChef.

Example

File chooser prompt in Google Chrome on MacOS
Example File Chooser Button in CyberChef using 'input' as the icon

[n1474335]

Closed in #478