This shadows ATOM used in js-regxp.

Making this an enum class requires changing a lot of different places.

Atom is an Intel brand name, so INTEL_ATOM kinda make sense.

Bug: v8:12244,v8:12245
Change-Id: I80be342488328cde5aaca36f900375d2fb381253
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3276926Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77875}