cppgc: Make RawHeap noncopyable

This is an attempt to fix a build failure in MSVC14.26.28801.

Bug: v8:10691
Change-Id: Ic4b994b14e1ac70ab95f3da53bd7be382e38a4b8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2300540Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68884}

src/heap/cppgc/raw-heap.h

@@ -48,6 +48,10 @@ class V8_EXPORT_PRIVATE RawHeap final {
   using const_iterator = Spaces::const_iterator;
 
   explicit RawHeap(HeapBase* heap, size_t custom_spaces);
+
+  RawHeap(const RawHeap&) = delete;
+  RawHeap& operator=(const RawHeap&) = delete;
+
   ~RawHeap();
 
   // Space iteration support.