[roll third_party/pigweed] pw_transfer: C++ service write support

This adds support for client-to-server write transfers to the C++
transfer service. Additionally, the transfer service is updated to
require the maximum chunk size as a constructor argument, as this
cannot easily be determined from the RPC system.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/56248

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 9634e72afffec29..563946f9fa728da
Roller-URL: https://ci.chromium.org/b/8838530486235878304
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8838530486235878304
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I1a8c03b2a37a5efc53e34edc6a0a8237f7a964c6
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/57587
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 9634e72..563946f 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 9634e72afffec292924559e8d3a0d0a81d162202
+Subproject commit 563946f9fa728da641a406dfdc7fa724abb770d2