roll: third_party/pigweed pw_containers: Make item type deduction generic

This CL moves generic intrusive container and item functions to a
standalone file, and renames them to avoid mentioning lists. This makes
them available to be reused by other intrusive containers, such as the
forthcoming intrusive maps.

Affected functions include the item type deduction checks for and the
assertions for containers and items before insertion or destruction.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/235105
Original-Revision: 7f4759a3877ac31bb0b0b2799a759d13382d9bba

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 25c8b842ecfa6d..7f4759a3877ac3
Roller-URL: https://ci.chromium.org/b/8736416068949802961
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I66f0efdc19f69afd7d2319ef66afd0a455a06d78
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/236782
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 25c8b84..7f4759a 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 25c8b842ecfa6d530b785d61c1fab105b352bcdd
+Subproject commit 7f4759a3877ac31bb0b0b2799a759d13382d9bba