[roll third_party/pigweed] pw_rpc: Improve Java client error message for missing parser() method

pw_rpc services currently store the class objects for generated
protobuf. Their parser() method is called using reflection to get an
object for parsing requests or responses. This fails in two situations:

- The class is not actually a generated protobuf class.
- The parser() method was optimized out (b/293361955).

This change improves the error message when calling parser(), adding a
reference to b/293361955. It also makes the class objects package
private to simplify transitioning to storing parsers in the future.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/159471

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 3ac2d484661504e..358c6172ead8855
Roller-URL: https://ci.chromium.org/b/8773827448302263665
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I78efafc8459e6bf53a5e9743a960fd4c8b3d7fbf
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/162353
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 3ac2d48..358c617 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 3ac2d484661504e3955c2a891a16ef3c701b92d1
+Subproject commit 358c6172ead88553e1d6eb5be5f2bd4491b7009c