* Prefix all isolate variables with i_ for i::Isolate and
  v8_ for v8::Isolate
* Change _DO_NOT_USE macro suffix to _INTERNAL

Change-Id: I005efbe0192cf202741448c63a4263e6a4b1fa1b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3610429
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80252}