[nolight132]

Summary

• merge 138 upstream gpui commits, from zed@d9ad6af to zed@56934ec
• carry layer filters, kawase blur, squircles, text shadows, variable font weights and idle target release onto upstream's split wgpu renderer and headless path
• keep atlas uploads written straight to the queue and drop the web and ios backends from the fork
• give a static font face one FontId across requested weights