Chrome is currently adding a 128-bit V8ContextToken to keep track of
V8 contexts across multiple isolates and processes. Having per-isolate
token exposed by V8 leads to confusion of these two tokens.

This moves v8::Context::Token to v8::metrics::Recorder and changes
the corresponding functions:
- v8::Context::GetToken => v8::metrics::Recorder::GetContextId
- v8::Context::GetByToken => v8::metrics::Recorder::GetContext

This CL is purely mechanical and does not change the behaviour.

Bug: chromium:1101749
Tbr: clemensb@chromium.org
Change-Id: I31bbfa02ebab1c0d91b00f0d08c1b236392d14d2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2330023
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Emanuel Ziegler <ecmziegler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69188}