roll: third_party/pigweed: pw_async2: Add more SimulatedTimeProvider utilities

These are useful for advancing test time without random
periods or endless iterations (e.g. advancing by 10ns
many many times).

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/234929
Docs-Not-Needed: Taylor Cramer <cramertj@google.com>

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 4cf921eb635b9b2..cfcbaf5bbc67288
Roller-URL: https://ci.chromium.org/b/8737035982232729169
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6a60e52e05eee273f989a1c0f749c59e77a14575
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/235182
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 4cf921e..cfcbaf5 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 4cf921eb635b9b23600d962de4b933cb80bf1635
+Subproject commit cfcbaf5bbc67288b5e8954f22528c4de9312effe