This CL does 2 things:
1) Implements forwarding of histogram reporting from cppgc to v8 via
CppHeap.
2) Establishes the pipeline in GCTracer for sending the histograms to
the embedder.

Currently only cppgc histograms are populated.

See crrev.com/c/2916956 for usage.

Bug: chromium:1154636
Change-Id: I8150116f757e105d0dfac96a3f6e7dd95717f5bd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2917033
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74830}