Extract gsvg_renderer from gcore, remove gcore/vello feature (#2760)

Extract `gsvg_renderer` from `gcore`, remove `gcore/vello` feature

node-graph/gcore/src/bounds.rs

@@ -0,0 +1,24 @@
+use crate::Color;
+use glam::{DAffine2, DVec2};
+
+pub trait BoundingBox {
+	fn bounding_box(&self, transform: DAffine2, include_stroke: bool) -> Option<[DVec2; 2]>;
+}
+
+macro_rules! none_impl {
+	($t:path) => {
+		impl BoundingBox for $t {
+			fn bounding_box(&self, _transform: DAffine2, _include_stroke: bool) -> Option<[DVec2; 2]> {
+				None
+			}
+		}
+	};
+}
+
+none_impl!(String);
+none_impl!(bool);
+none_impl!(f32);
+none_impl!(f64);
+none_impl!(DVec2);
+none_impl!(Option<Color>);
+none_impl!(Vec<Color>);