roll: third_party/pigweed: pw_grpc: Improve logging when receiving unknown RPC

This commit improves the logging of pw_grpc when receiving an RPC for
which the server has no handler.

Previously, logs would only show 'Could not find method type', without
any indication of what the RPC method was.

As part of this change, the pw_rpc server and method are looked up once
when the stream is connected, rather than repeatedly each time a message
is received on the stream.

Test: Send an unknown RPC, observe that a more helpful message is
Test: printed, with the full name of the gRPC method.
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/231011

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 234632dd4e30bd4..674e839b7f0eda3
Roller-URL: https://ci.chromium.org/b/8738983947290521969
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ia76c6a6f6aea3568ca53b505874d5ee0fa4a1ac7
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/231152
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 234632d..674e839 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 234632dd4e30bd45ca03b075eb5f75c6acb70d64
+Subproject commit 674e839b7f0eda3be510baa012a95cb6cb44a29c