Implement TransformObject for Handle<Curve>

This is preparation for setting curve geometry there.

crates/fj-core/src/operations/transform/curve.rs

@@ -1,19 +1,24 @@
 use fj_math::Transform;
 
-use crate::{topology::Curve, Core};
+use crate::{
+    operations::insert::Insert, storage::Handle, topology::Curve, Core,
+};
 
 use super::{TransformCache, TransformObject};
 
-impl TransformObject for Curve {
+impl TransformObject for Handle<Curve> {
     fn transform_with_cache(
         &self,
         _: &Transform,
-        _: &mut Core,
-        _: &mut TransformCache,
+        core: &mut Core,
+        cache: &mut TransformCache,
     ) -> Self {
         // There's nothing to actually transform here, as `Curve` holds no data.
         // We still need this implementation though, as a new `Curve` object
         // must be created to represent the new and transformed curve.
-        Self::new()
+        cache
+            .entry(self)
+            .or_insert_with(|| Curve::new().insert(core))
+            .clone()
     }
 }