[roll third_party/pigweed] pw_system: Add log timestamp and console support

- Use time since boot as timestamp
- Remove obsolete TODOs
- Support log drop count message
- Print timestamp in a human-readable way
- Provide option for user-defined timestamp decoding

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/78281

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 803ea919f613332..4987fafe0091d1b
Roller-URL: https://ci.chromium.org/b/8825120785469834689
Cq-Cl-Tag: roller-builder:pigweed-sample-project-roller
Cq-Cl-Tag: roller-bid:8825120785469834689
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I6949509f5ea423b2ac29fd268b39ca1873b6afaf
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/sample_project/+/78566
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 803ea91..4987faf 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 803ea919f61333289ec215a58c9b53f0f781119d
+Subproject commit 4987fafe0091d1bdeedeccd451477c48c1e87bc3