Update attachment type previews

[grantfitzsimmons]

https://github.com/specify/specify6/tree/master/src/edu/ku/brc/specify/images

Most of the attachment images were created/uploaded nearly 15 years ago, on Feb 8, 2008. Specify 7 is still using these all this time later.

We should consider using icons in place of these images based on the file type, or design high-quality images to take the place.

specify/specify6@bab050c

This needs to be done either by updating the 6 files or changing the display behavior in 7.