This CL adds Heap::FreeLinearAllocationAreas to free all local
allocation buffers (LABs). We use this to give up LABs for a local GC.
The second method Heap::FreeSharedLinearAllocationAreas is used to free
all LABs in the shared heap for shared GCs and in the future also on
isolate shutdown.

Bug: v8:10315
Change-Id: Ie5cbb68c95fae027055aeaf4458473b04b15b18c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3279681Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77900}