Add a “duplicate current image” button

[Kuronoe-Ookami]

System information

• Windows OS version: Windows 10.
• ImageGlass version: latest version 9.1.8.723.
• ImageGlass release: Classic?

Describe the feature

Add a “duplicate current image” button. For people who make batch variations of images and datasets for use in IA, this is a good idea if you don't want to lose a good image.

I'm still testing it, but it's much better than the image viewers I've been shown so far ⭐