refactor: make shallow_move() available from AGCObjectVisitor

idl/GCObjectVisitor.json5

@@ -57,6 +57,22 @@
 //        },
     ],
     nonconst_methods: [
+        // void alloc_copy(void * src)
+        {
+            name: "alloc_copy",
+            doc: [
+                "allocate copy of source object at address @p src.",
+                "Source must be owned by this collector.",
+                "Increments object age"
+            ],
+            return_type: "void *",
+            args: [
+                {type: "std::byte *", name: "src"},
+            ],
+            const: false,
+            noexcept: false,
+            attributes: [],
+        },
         // void visit_child(AGCObject * iface, void ** pp_data) noexcept;
         {
             name: "visit_child",