[Feature Request] Custom cover enhancement

[abillauer]

Thanks for the custom cover system!

It would be cool if in codex you could click on a comic or folder and click on the three dots (that say "mark as read") and you could choose an option for set as cover for folder. This would set the image you selected as the image for the parent folder.

This would give an easy, in-system way of setting custom folder covers.
Thanks