[roll third_party/pigweed] pw_log: Add log proto encode helper for strings

Adds a Log message encode helper for string-based logging where no
information may be practically tokenized.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/77181

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: dad98c15ae9a215..bca005a5a54d7a5
Roller-URL: https://ci.chromium.org/b/8824400136431575617
Cq-Cl-Tag: roller-builder:pigweed-experimental-roller
Cq-Cl-Tag: roller-bid:8824400136431575617
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I741593ae2ad85b34c4884be307517970c7e60137
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/80822
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 dad98c1..bca005a 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit dad98c15ae9a21530f6ddc97c7f7a97eeaadfd95
+Subproject commit bca005a5a54d7a5a149b42cc2a14d6db4f7e2925