Add images to cards

[david-swift]

trafficstars

Is your feature request related to a problem? Please describe.

No response

Describe the solution you'd like

@wada3n reported in #1 that it would make sense to add an image to a flashcard. I would add another button to a flashcard's toolbar (maybe make it one media button together with #3) for the image. Similarly to #3, this would be hidden by default and displayed in a popover in all the views.

Describe alternatives you've considered

One might also display the image in the flashcard next to the text (on the top), and in the study and test view to the question, but this solution is not ideal as an image can illustrate the question as well as the answer.

Additional context

This problem has been reported by @wada3n in #1.

[lightonflux]

It would be great if there was also a hook to the system's screenshot tool. That way a user could press a button and select an area on the screen to "import" parts of a slide of a PDF.

https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.Screenshot.html#screenshot