ART: Add heap iteration callback

Add callback support for heap iteration. Visiting of fields will
be done in a follow-up.

Add a test.

Bug: 31385354
Test: m test-art-host-run-test-906-iterate-heap
Test: m ART_TEST_GC_STRESS=true ART_TEST_GC_VERIFY=true test-art-host-run-test-906-iterate-heap
Change-Id: I7bcf6751e6df4ef58756ba97701050b2ff5eb07b
diff --git a/test/ti-agent/common_load.cc b/test/ti-agent/common_load.cc
index 2b8947e..c412636 100644
--- a/test/ti-agent/common_load.cc
+++ b/test/ti-agent/common_load.cc
@@ -29,6 +29,7 @@
 #include "903-hello-tagging/tagging.h"
 #include "904-object-allocation/tracking.h"
 #include "905-object-free/tracking_free.h"
+#include "906-iterate-heap/iterate_heap.h"
 
 namespace art {
 
@@ -50,6 +51,7 @@
   { "903-hello-tagging", Test903HelloTagging::OnLoad, nullptr },
   { "904-object-allocation", Test904ObjectAllocation::OnLoad, nullptr },
   { "905-object-free", Test905ObjectFree::OnLoad, nullptr },
+  { "906-iterate-heap", Test906IterateHeap::OnLoad, nullptr },
 };
 
 static AgentLib* FindAgent(char* name) {