[roll third_party/pigweed] pw_rpc: Fix destructor ordering problem in test helpers

During destruction, the FakeChannelOutput& in the InvocationContext base
class would be used to send a final RPC message. The ChannelOutput
instance it pointed to was in a derived class, so would be destructed
before the RPC packet was sent, resulting in "pure virtual function
call" crashes in tests.

- Move the FakeChannelOutput instance to the base InvocationContext so
  it is destructed last, after any responses are sent.
- Explicitly delete some copies/moves.
- Fix typo in transfer_test.cc.
- Handle some ignored Status returns.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/59761

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 79ea2cf5dd7a766..2a70d8f6e5c4d87
Roller-URL: https://ci.chromium.org/b/8836707586379220609
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8836707586379220609
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I83aa5e4f03f25a21b0198206b12fa49ce6190c4d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/60021
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 79ea2cf..2a70d8f 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 79ea2cf5dd7a766efbfb2c8d9f1019aa983e79e8
+Subproject commit 2a70d8f6e5c4d87d23629423e01543b386467f92