pw_rpc: Utilities for testing RPC service methods

Define the PW_RPC_TEST_METHOD_CONTEXT macro, which declares a context
object that can be used to invoke service methods in tests.

Change-Id: I829c7e4f73265ba4c6c2e9ae6ff0cd16fe1fb2a5
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/14025
Commit-Queue: Wyatt Hepler <hepler@google.com>
Reviewed-by: Alexei Frolov <frolv@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
diff --git a/pw_rpc/channel_test.cc b/pw_rpc/channel_test.cc
index c2938dc..74e691a 100644
--- a/pw_rpc/channel_test.cc
+++ b/pw_rpc/channel_test.cc
@@ -16,7 +16,7 @@
 
 #include "gtest/gtest.h"
 #include "pw_rpc/internal/packet.h"
-#include "pw_rpc_private/test_utils.h"
+#include "pw_rpc_private/internal_test_utils.h"
 
 namespace pw::rpc::internal {
 namespace {