Remove Builder abstractions for gradients

graphics/src/geometry/fill.rs

@@ -1,8 +1,8 @@
 //! Fill [crate::widget::canvas::Geometry] with a certain style.
-use iced_core::Color;
-
 pub use crate::geometry::Style;
-use crate::Gradient;
+
+use crate::core::Color;
+use crate::gradient::{self, Gradient};
 
 /// The style used to fill geometry.
 #[derive(Debug, Clone)]
@@ -50,6 +50,15 @@ impl From<Gradient> for Fill {
     }
 }
 
+impl From<gradient::Linear> for Fill {
+    fn from(gradient: gradient::Linear) -> Self {
+        Fill {
+            style: Style::Gradient(Gradient::Linear(gradient)),
+            ..Default::default()
+        }
+    }
+}
+
 /// The fill rule defines how to determine what is inside and what is outside of
 /// a shape.
 ///