[Improvement] Saving image in WebP format when importing image [dev1.10.0.38]

[NEKolev]

I did some tests with the image transparency option enabled and it turned out that when importing from the American Numismatic Society, I guess also from Colnect, the image is saved in the database in JPEG format. In my opinion, this is not correct and they should be saved in WebP format. Many of the images may have a transparent background in ANS/Colnect.

Importing from Excel should also save the images in WebP format in my opinion (I haven't tested it, but I guess it behaves similarly).