[roll third_party/pigweed] pw_protobuf: Add StreamDecoder

This adds a protobuf decoder that operates on stream readers instead of
buffers. It exists as a parallel implementation to the buffer decoder.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/58744

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 71ee193e797b49a..03e1b265752f327
Roller-URL: https://ci.chromium.org/b/8836189387721624385
Cq-Cl-Tag: roller-builder:pigweed-sample-project-roller
Cq-Cl-Tag: roller-bid:8836189387721624385
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ibe0c82a29f7ae859b5a92cb77c436630c6963f7b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/sample_project/+/60691
Bot-Commit: 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 71ee193..03e1b26 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 71ee193e797b49a11775fa5f8cbfc00673e5fb0e
+Subproject commit 03e1b265752f327972242e634e2029c416536ad9