The goal of the PR is to add to telemetry a metric estimating the space
occupied by the codemap retained by a CpuProfiler and its underlying
CodeObserver.

This change is motivated by the addition of kEagerLogger to CpuProfiler
which when enabled let a CpuProfiler build a CodeMap without an active
session. This metric will help us understand better the space consumed
by a profiler in that scenario and will also help detect memory leaks.

Bug: chromium:1241491
Change-Id: Iadb1ed52b4c1ac70bc554942b4fa795cdf1212f3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3224567Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Auto-Submit: Corentin Pescheloche <cpescheloche@fb.com>
Cr-Commit-Position: refs/heads/main@{#77703}