[wasm] Add missing V8_EXPORT_PRIVATE annotations

Since {CodeSpaceWriteScope} is now used from cctests (since
https://crrev.com/c/3024150), its constructor and destructor need to be
exported.

R=jkummerow@chromium.org

Change-Id: I30627d632a9f4e4fde51bcb037bad69ceaedf6fd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3038062
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75786}

src/wasm/code-space-access.h

@@ -45,8 +45,8 @@ class NativeModule;
 // permissions for all code pages.
 class V8_NODISCARD CodeSpaceWriteScope final {
  public:
-  explicit CodeSpaceWriteScope(NativeModule* native_module);
-  ~CodeSpaceWriteScope();
+  explicit V8_EXPORT_PRIVATE CodeSpaceWriteScope(NativeModule* native_module);
+  V8_EXPORT_PRIVATE ~CodeSpaceWriteScope();
 
   // Disable copy constructor and copy-assignment operator, since this manages
   // a resource and implicit copying of the scope can yield surprising errors.