Publishing Wasm code often happens in a loop (in particular for
deserialization), so hold the {CodeSpaceWriteScope} outside that loop to
avoid repeated switching between writable and executable.

R=ahaas@chromium.org

Bug: v8:11974, chromium:1297999
Change-Id: Ic4bf859685e66c4ba297fed968d0df6ae7d24cba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3468896Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79135}