[roll third_party/pigweed] pw_{log, log_rpc}: Separate Filter Service

- Separate the log and log filter services to make the first not rely on
the second.
- Separated unit tests for both services with minor fixes to existing
unit tests.
- Updated documentation.

Original-Fixes: 570
Original-Requires: pigweed-internal:18860
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/72502

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: cc9f186da4b85cd..e4be88b8eafb635
Roller-URL: https://ci.chromium.org/b/8825389370627500593
Cq-Cl-Tag: roller-builder:pigweed-sample-project-roller
Cq-Cl-Tag: roller-bid:8825389370627500593
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: Ie7f959fb41dc4ea123afe817e8ebcfb034dad5eb
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/sample_project/+/77781
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 cc9f186..e4be88b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit cc9f186da4b85cdfeef67bc6fc8cd1c5656b0fe7
+Subproject commit e4be88b8eafb6354b31cd1aff5fd00fb36adc387