[roll third_party/pigweed] pw_presubmit: Allow customizing black

Allow customizing the executable used for black. Also, explicitly
specify a config file for black if one is present in a couple locations.
It now looks at the following locations, in order:

* $PW_PROJECT_ROOT/.black.toml
* $PW_PROJECT_ROOT/pyproject.toml
* $PW_ROOT/.black.toml
* $PW_ROOT/pyproject.toml

Original-Bug: b/264578594
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/126211

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 352fe28de3f3467..a19b9fd3a8b35d5
Roller-URL: https://ci.chromium.org/b/8790936442162023889
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I704de6a6817b8a52cff8d4f8049561b7d355aa84
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/126945
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 352fe28..a19b9fd 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 352fe28de3f34675ed30553629590aa329d66f98
+Subproject commit a19b9fd3a8b35d5d206a1793f19be6398d49c90f