On most platforms, we can do a single allocation for all code. On
platforms where this is not possible (e.g. ARM64 has a 128MB code space
limit), we will at least allocate big chunks instead of one chunk per
function. This reduces overhead in {WasmCodeAllocator} for maintaining
sets of used and available code space, and reduces locking during
deserialization.

In order to know how much code space to pre-allocate, the serializer
writes out the total code space size. This is then used during
deserialization to know how much code to expect.

R=thibaudm@chromium.org

Bug: v8:11164
Change-Id: If3846292544c7b6832b7a0b56357b74310f6fb23
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2644942
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72317}