This CL adds a flag to reduce the initial code space reservation size
(--wasm-max-initial-code-space-reservation), and adds a test which creates at
least four separate code spaces and calls between them.

R=mstarzinger@chromium.org

Bug: v8:9477
Change-Id: I1b4c430266962eb94dbe4b381f46b03c2ec07fc2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1782999
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63797}