[roll pigweed] pw_env_setup: Add stderr error shell functions

Add shell error functions that write to stderr.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/104941

https://pigweed.googlesource.com/pigweed/pigweed
pigweed Rolled-Commits: 82ce71e4a5e7b14..a555370f692b554
Roller-URL: https://ci.chromium.org/b/8806733902129195937
Cq-Cl-Tag: roller-builder:pigweed-zephyr-roller
Cq-Cl-Tag: roller-bid:8806733902129195937
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I218fd3b16330dcc0fb07d67c642ff2b19bf936da
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/zephyr-integration/+/105001
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/pigweed b/pigweed
index 82ce71e..a555370 160000
--- a/pigweed
+++ b/pigweed
@@ -1 +1 @@
-Subproject commit 82ce71e4a5e7b140cc2222f2fc7a26fde7997a5e
+Subproject commit a555370f692b554349ee69ec6c07a6f93ca6b927