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}