[roll third_party/pigweed] pw_env_setup: Adds CIPD deps to Bazel workspace

This adds a set of repository rules to generate a set of Bazel macros
that configure pigweeds CIPD deps.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/53480

third_party/pigweed Rolled-Commits: 843d427438c1e58..68ef2a59c2ccaba
Roller-URL: https://ci.chromium.org/b/8840414554444688224
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8840414554444688224
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I9ed2a38c84bfba94bc7721de0cf3df50d8be0c11
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/55050
Reviewed-by: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 843d427..68ef2a5 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 843d427438c1e58f2a605e4194e9bcec2c27991b
+Subproject commit 68ef2a59c2ccabaef5f3662d5cac56f0f3c85942