gpui: Render SVGs at 2x size when rendered in an img (#24332)

This PR adjusts the rendering of SVGs when used with the `img` element
such that they are rendered at 2x their displayed size.

This results in much crisper icons for icons loaded by icon themes:

<img width="1136" alt="Screenshot 2025-02-05 at 7 39 48 PM"
src="https://github.com/user-attachments/assets/47d1fcee-c54d-4717-8fca-9b9d2bc8da9a"
/>

<img width="1136" alt="Screenshot 2025-02-05 at 7 40 01 PM"
src="https://github.com/user-attachments/assets/3061157c-8c88-41c1-a5dc-83ef9cd341cb"
/>

Release Notes:

- Improved the resolution of icons rendered by icon themes.

crates/gpui/src/elements/img.rs

@@ -3,6 +3,7 @@ use crate::{
     DefiniteLength, Element, ElementId, GlobalElementId, Hitbox, Image, InteractiveElement,
     Interactivity, IntoElement, LayoutId, Length, ObjectFit, Pixels, RenderImage, Resource,
     SharedString, SharedUri, StyleRefinement, Styled, SvgSize, Task, Window,
+    SMOOTH_SVG_SCALE_FACTOR,
 };
 use anyhow::{anyhow, Result};
 
@@ -610,7 +611,7 @@ impl Asset for ImageAssetLoader {
             } else {
                 let pixmap =
                     // TODO: Can we make svgs always rescale?
-                    svg_renderer.render_pixmap(&bytes, SvgSize::ScaleFactor(1.0))?;
+                    svg_renderer.render_pixmap(&bytes, SvgSize::ScaleFactor(SMOOTH_SVG_SCALE_FACTOR))?;
 
                 let mut buffer =
                     ImageBuffer::from_raw(pixmap.width(), pixmap.height(), pixmap.take()).unwrap();