`<use>` elements don't work in SVG costumes (and the Rays backdrop)

Expected Behavior

Those <use> elements that reference an element inside the costume are rendered normally

Actual Behavior

All <use> elements are removed

This prevents the Rays backdrop from showing up, because it has a clip path with a <use> element applied to everything (https://scratch.mit.edu/discuss/topic/842302/)

It also prevents the dropdown arrows and the pen icon in scratchblocks SVGs from showing up

Steps to Reproduce

Steps to reproduce the behavior:

1. Go to 'https://scratch.mit.edu/projects/editor/'
2. Add the 'Rays' backdrop
3. The backrop appears in the Stage thumbnail, but not on the stage canvas because the <use> element is removed

System Details

• Windows 10, Chrome 141

from https://scratch.mit.edu/discuss/topic/842302/:

• ChromeOS 14541, Chrome 138
• Windows 7, Chrome 139
• Windows 7, Chrome 109

Screenshots

Reproduce the problem in the Scratch project editor with the Rays backdrop and an SVG containing a element. Start by tracing the SVG costume rendering path from the editor, then compare the rendered costume with its source SVG. Done means referenced elements remain available so the Rays backdrop, dropdown arrows, and pen icon render normally.