[meshcat] Track breaking change in newer meshcat's three.js (#22975)

- change capsule 'length' to 'height'

Author: vincekurtz

geometry/meshcat.cc

@@ -589,7 +589,7 @@ class MeshcatShapeReifier : public ShapeReifier {
     auto geometry = std::make_unique<internal::CapsuleGeometryData>();
     geometry->uuid = uuid_generator_.GenerateRandom();
     geometry->radius = capsule.radius();
-    geometry->length = capsule.length();
+    geometry->height = capsule.length();
     lumped.geometry = std::move(geometry);
 
     // Meshcat cylinders have their long axis in y.

geometry/meshcat_types_internal.h

@@ -211,7 +211,7 @@ struct CapsuleGeometryData : public GeometryData {
   // For a complete description of these parameters see:
   // https://threejs.org/docs/#api/en/geometries/CapsuleGeometry
   double radius{};
-  double length{};
+  double height{};
   double radialSegments{20};  // Number of segmented faces around the
                               // circumference of the capsule.
   double capSegments{10};     // Number of curve segments used to build
@@ -224,7 +224,7 @@ struct CapsuleGeometryData : public GeometryData {
     o.pack("CapsuleGeometry");
     PACK_MAP_VAR(o, uuid);
     PACK_MAP_VAR(o, radius);
-    PACK_MAP_VAR(o, length);
+    PACK_MAP_VAR(o, height);
     PACK_MAP_VAR(o, radialSegments);
     PACK_MAP_VAR(o, capSegments);
   }