This CL adds 2 new values to the EmbedderStackState enum with more
explicit names. The old values are updated as aliases to the new
values and marked as soon to be deprecated. This CL also moves the
enum to v8-platform.h so that it can be reused by cppgc.

Depracating individual values in an enum is supported by GCC only
since version 6. Thus new macros were needed for the deprecation
(which delegate to the existing macros when supported). GCC versions
older than 6 are still used by the CQ bots.

Bug: chromium:1056170
Change-Id: Id1ea73edfbbae282b0d8a3bb103dbbbf8ebd417e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2188971
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67744}