[roll third_party/pigweed] pw_gpio: Add new module and interfaces

NOTE: this module will be renamed `pw_digital_io` immediately in a
follow-up change.

The Digital IO interface represents individual GPIO lines that support
some combination of input, output, and/or interrupt functionality.
The choice of supported capability, and most other configuration details
are left up to the backend implementation.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/94100

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: d4e68a17b860f9a..f66bf12f1b67904
Roller-URL: https://ci.chromium.org/b/8811164503423148289
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811164503423148289
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I34276620e56273153e75dd67723ad9e09bdd2b9f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/98495
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index d4e68a1..f66bf12 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit d4e68a17b860f9a7cb52fb5177081975a0f59f51
+Subproject commit f66bf12f1b67904eaedebaf306277a94b78db0e4