This is a reland of commit e2066ff6

Changes since revert:
- Rebased against c9918524, which
  uses the external pointer table for the WaiterQueueNode stored
  in the state field when compressing pointers. This relaxes
  the alignment requirement of the state field to be 4-bytes when
  compressing pointers.
- Moved the state field into the JSSynchronizationPrimitive base
  class, since alignment and padding can now be made simpler.

Original change's description:
> [shared-struct] Add Atomics.Condition
>
> Bug: v8:12547
> Change-Id: Id439aef9cab3348171a23378cdd47ede5f4d7288
> Cq-Include-Trybots: luci.v8.try:v8_linux_arm64_rel_ng,v8_linux64_tsan_rel_ng
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3630350
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Commit-Queue: Shu-yu Guo <syg@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#81734}

Bug: v8:12547
Change-Id: I638304c3d5722c64bd04708ed4cf84863cdebb81
Cq-Include-Trybots: luci.v8.try:v8_linux_arm64_rel_ng,v8_linux64_tsan_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3763787Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82278}