OptimizationDecision holds the optimization {reason, code kind,
concurrency mode}. We centralize it to avoid having to recalculate in
Optimize when we already know everything in ShouldOptimize.

Bug: v8:7700
Change-Id: Ifcd902e86f844ce045bcefd4ae72ac17b42acb3a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3500300
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79326}