Add files to test linked images in SVG images

[tovrstra]

These are some small test files related to typst/typst#6794

They can be used in the following typst document for testing:

#set page(width: auto, height: auto, margin: 1pt)
#set text(1pt)
#image("link-gif.svg")
#image("link-jpeg.svg")
#image("link-jpg.svg")
#image("link-png.svg")
#image("link-webp.svg")

[laurmaedje]

It's kinda a lot of files. The small images are nice and could come in handy in other tests, but the linking SVGs less so. Maybe we could just link to all files from a single SVG?

[tovrstra]

Good point. I've put them all in one linked SVG with some graphics in front and behind the linked images. I've also further optimized the byte size of the bitmaps a bit and made them more cheerful!

I hope the force push is ok. It seemed better to get rid of the commit with the previous iteration of the bitmaps.

[laurmaedje]

You can push however you like, I'll squash on merge anyway. :) Is this ready for merge?

[tovrstra]

Yes, I've used it in a manual test with the code in PR typst/typst#6794 and all looks good.

This is the test file:

#set page(width: auto, height: auto, margin: 1pt)
#set text(1pt)
#image("linked.svg")

[laurmaedje]

Thanks!