[roll third_party/pigweed] pw_unit_test: Add test record event handler

This CL creates a new test event handler that will output a test summary
in json format. The format is described in detail here:
https://chromium.googlesource.com/chromium/src/+/refs/tags/66.0.3359.15/docs/testing/json_test_results_format.md

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/194050

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: a40cea068aab447..1db68c304885566
Roller-URL: https://ci.chromium.org/b/8753447480414282401
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I00df288bb1a88bed8441624f2066f97a0c258acd
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/196830
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 a40cea0..1db68c3 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit a40cea068aab4477b6a636e4ebce7e8d7c45a608
+Subproject commit 1db68c3048855662526222fe4ae0a0230902cb4e