[K/N] custom-alloc: handle finalizers

This commit adds finalizers to the custom allocator. Compared to the
existing solution:

* The finalizer queue is replaced by an AtomicStack<ExtraObjectData>.
* All objects with finalizers get meta objects attached. This was not
  previously the case for CleanerImpl, but is now needed to link objects
  together in the finalization queue.
* The finalizer queue is built during SweepExtraObjects, instead of
  during regular sweeping.
* Cleaners are executed by the finalizer thread, and no longer by a
  separate worker thread.

Co-authored-by: Troels Lund <troels@google.com>

Merge-request: KOTLIN-MR-592
Merged-by: Alexander Shabalin <alexander.shabalin@jetbrains.com>

kotlin-native/runtime/src/mm/cpp/Memory.cpp

@@ -86,8 +86,10 @@ void ObjHeader::destroyMetaObject(ObjHeader* object) {
     RuntimeAssert(object->has_meta_object(), "Object must have a meta object set");
     auto &extraObject = *mm::ExtraObjectData::Get(object);
     extraObject.Uninstall();
+#ifndef CUSTOM_ALLOCATOR
     auto *threadData = mm::ThreadRegistry::Instance().CurrentThreadData();
     mm::ExtraObjectDataFactory::Instance().DestroyExtraObjectData(threadData, extraObject);
+#endif
 }
 
 ALWAYS_INLINE bool isPermanentOrFrozen(const ObjHeader* obj) {