Import and export cards from JSON

**Describe your feature request** _{Describe your ideas for this new feature and how it should be implemented} This feature would allow the user to export one or all of their cards to JSON for backup, editing purposes, or to move cards to another account **Additional information regarding your feature** _{Add more details or concept art} This should add a button to the context menu on the `/home` page for each card and for all of the cards that the user created and somewhere on the `/editor` page. It would download a `.json` file which would be everything from the `data` field on the `Card` model Additionally some manipulation of the data when the card is imported via the `/home` page would be needed, like removing the UUID parameter and allowing the server to generate that