xo-gc: refactor: demote GCObjectVisitor to GCObjectStore

No longer needed by DX1Collector
Also retires utest/MockCollector

xo-gc/src/gc/DGCObjectStoreVisitor.cpp

@@ -0,0 +1,54 @@
+/** @file DGCObjectStoreVisitor.cpp
+ *
+ *  @author Roland Conybeare, Apr 2026
+ **/
+
+#include "GCObjectStoreVisitor.hpp"
+#include "GCObjectStore.hpp"
+
+namespace xo {
+    namespace mm {
+
+        DGCObjectStoreVisitor::DGCObjectStoreVisitor(GCObjectStore * gcos,
+                                                     Generation upto)
+        : p_gco_store_{gcos}, upto_{upto}
+        {}
+
+        Generation
+        DGCObjectStoreVisitor::generation_of(Role r, const void * addr) const noexcept
+        {
+            return p_gco_store_->generation_of(r, addr);
+        }
+
+        AllocInfo
+        DGCObjectStoreVisitor::alloc_info(void * mem) const noexcept
+        {
+            return p_gco_store_->alloc_info((std::byte *)mem);
+        }
+
+        void
+        DGCObjectStoreVisitor::visit_child(VisitReason reason,
+                                           AGCObject * lhs_iface, void ** lhs_data)
+        {
+            switch (reason.code()) {
+            case VisitReason::code::forward:
+                p_gco_store_->forward_inplace_aux
+                    (this->ref<AGCObjectVisitor>(), lhs_iface, lhs_data, upto_);
+                break;
+            case VisitReason::code::verify:
+                p_gco_store_->verify_aux(lhs_iface, *lhs_data);
+                break;
+            default:
+                assert(false);
+            }
+        }
+
+        std::byte *
+        DGCObjectStoreVisitor::alloc_copy(void * src) noexcept {
+            return p_gco_store_->new_space()->alloc_copy((std::byte *)src);
+        }
+
+    } /*namespace mm*/
+} /*namespace xo*/
+
+/* end DGCObjectVisitor.cpp */