[roll third_party/pigweed] pw_software_update: Add finalize and manifest get/update for backend

Add get/update methods for the current manifest in the update backend.
Add FinalzeUpdate method to finish the update and trigger the device
reboot.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/61621

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 39d85f512409b26..054771a4e3d65d5
Roller-URL: https://ci.chromium.org/b/8835446099756866545
Cq-Cl-Tag: roller-builder:pigweed-sample-project-roller
Cq-Cl-Tag: roller-bid:8835446099756866545
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I459ccb7400d8cf652286c872f1ce88519524d8ea
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/sample_project/+/61663
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 39d85f5..054771a 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 39d85f512409b267140e463f486791e965d0b4f5
+Subproject commit 054771a4e3d65d5e14772cf97902a1b01f47fed7