Rerasterize SVGs when resized and refactor a bit

wgpu/src/primitive.rs

@@ -1,6 +1,6 @@
 use iced_native::{
-    image, Background, Color, Font, HorizontalAlignment, Rectangle, Vector,
-    VerticalAlignment,
+    image, svg, Background, Color, Font, HorizontalAlignment, Rectangle,
+    Vector, VerticalAlignment,
 };
 
 /// A rendering primitive.
@@ -46,6 +46,14 @@ pub enum Primitive {
         /// The bounds of the image
         bounds: Rectangle,
     },
+    /// An SVG primitive
+    Svg {
+        /// The path of the SVG file
+        handle: svg::Handle,
+
+        /// The bounds of the viewport
+        bounds: Rectangle,
+    },
     /// A clip primitive
     Clip {
         /// The bounds of the clip