Improve SVG imports for images with some styling, etc.

[nfd9001]

Making a new issue per the request in #9373. Note that clicking through the link for the lineart has a full SVG, which you should be able to open up in your text editor (etc.) as needed. If you need more examples, please let me know, and do feel free to change this issue title as appropriate.

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(re: preview png/svg import feature announced in-thread) Looks pretty promising in change description in the slicer preview! A feature like this could be really great for a project I'm working on with an artist right now; sadly it isn't quite working with the feature that's out in this first slicer alpha. He's been using a drawing app on an Android tablet to draw baseplates and lineart, exporting rasters, and then using https://vectorizer.ai/ (any old tool like this could work) to export vectors I can work with more easily in e.g. Fusion360. Here's an actual example of a file I tried to import and what I got:

Not quite right.

This process obviously wouldn't create super-clean vectors with strictly only shape data, like one might get out of InkScape, so I wasn't expecting that it'd necessarily immediately work. I just think it'd be worth documenting what sorts of features are supported, and if being a bit more permissive of input in some specific way seemed worth a new issue, I could see about making one.

Originally posted by @nfd9001 in #9373 (comment)

[Jony01]

I see in inkscape there is white shape for background.

Fixed svg:


When you delete white background everything is working ;-)