[roll third_party/pigweed] pw_protobuf: Add StreamEncoderCast<>()

Adds a helper template to make casting between StreamEncoder types
easier to read.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/97909

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 86312ba21e9d173..f04cd244725ec24
Roller-URL: https://ci.chromium.org/b/8811159795610319505
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811159795610319505
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I4cd2af8c96819a312aaa12ce2135c5261e1c912e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/98544
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 86312ba..f04cd24 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 86312ba21e9d173296a5c20ad474362291f9c080
+Subproject commit f04cd244725ec24f2a4ae886f70573aa2e7c9d9f