roll: third_party/pigweed pw_async2: Introduce codelab step 5 solution

- Implements the solution for step 5, which involves communicating
  between two tasks, and polling for timeouts.
- Adds a hardware command to simulate turning a motor on or off for an
  item slot, as well as an isr for an "item drop" sensor indicating an
  item drop.
- Adjusts the prior steps so the item drop isr is stubbed out.
- Adjusts the prior step BUILD.bazel files so the dependencies are
  already configured in anticipation of step 5.

All solutions (and the base code) build and run.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/319232
Original-Revision: 57f5fb8ce6063b7ff4fc54a045032510ee5f76fe

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 8df80e6d1b10d5..57f5fb8ce6063b
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8704586769913538145
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I0dc2f87ca997cc968bf36548efd430692f0ef438
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/320072
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 8df80e6..57f5fb8 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 8df80e6d1b10d5abbe75463a845c5b737518158e
+Subproject commit 57f5fb8ce6063b7ff4fc54a045032510ee5f76fe