Provide a global memory controller used to compute limits for combined
on-heap and embedder memory. The global controller uses the same
mechanism (gc speed, mutator speed) and growing factors as the regular
on-heap controller.

Rely on V8's mechanisms for configured state that stops shrinking the
limit.

This reverts commit 5e043f27.

Tbr: ulan@chromium.org
Bug: chromium:948807
Change-Id: Id4f94e7dcb458d1d0d2f872194f8f3ea0959a73f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1622968Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61715}