This ports HeapStatsCollector (former ThreadHeapStatsCollector) from
Blink. The CL only ports accounting of allocated object size which is
needed for a simple growing strategy in a follow up.

HeapStatsCollector is a global dependency for most sub components as
it provides infrastructure for measuring time (through trace scopes)
and space.

The general idea of HeapStatsCollector is to act as sink where all sub
components push time and space information. This information is then
gathered and made available via an event that is implemented as POD.
Time-dependent info is available through regular getters (pull) and
observers (push).

Change-Id: I40b4d76e1a40c56e5df1a7353622318cde730e26
Bug: chromium:1056170
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2225902
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68150}