[roll third_party/pigweed] pw_rpc: Add Request/Response types for raw MethodInfo

Both pwpb and nanopb implementations define Request and Response types
in MethodInfo specialization. For raw they are marked as void to prevent
any ConstByteSpan shallow copying.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/97905

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: fd3ebed4472e839..803298e1237eb56
Roller-URL: https://ci.chromium.org/b/8811260483745325809
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8811260483745325809
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I81171008fa08c70f16ff4909314ff0a2d7fd3951
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/98225
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 fd3ebed..803298e 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit fd3ebed4472e839adc4cc6e30b0ab23d7db0a04e
+Subproject commit 803298e1237eb56ea96d1c7b69b093d0d553f1bc