roll: third_party/pigweed pw_bluetooth_sapphire: Use services in virtual HCI

Publish fuchsia.hardware.bluetooth.Service from bt_hci_virtual and
remove the legacy bt-hci devfs nodes from EmulatorDevice and
LoopbackDevice now that Fuchsia test harnesses watch the service
directly.

Also clean up LoopbackDevice lifecycle and initialization handling
(unpublishing on channel peer close, guarding unbound node removal on
init failure, and passing string_view safely to NodeAddArgs).

Original-Bug: b/430578502
Test: bazelisk build --config=fuchsia //pw_bluetooth_sapphire/fuchsia/bt_hci_virtual:pkg.x64 //pw_bluetooth_sapphire/fuchsia/bt_hci_virtual:test_pkg
Test: (fuchsia) fx test bt-access-integration-tests bt-le-integration-tests
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/498013
Original-Revision: 414050ba2a04f9e337971ee1664f92bbd0511838

Rolled-Repo: https://pigweed.googlesource.com/pigweed/pigweed
Rolled-Commits: 06cf2cf0cb4d5c..414050ba2a04f9
Roll-Count: 1
Roller-URL: https://cr-buildbucket.appspot.com/build/8668034757174376705
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I1bebb0f7b33f86b9dfcd0a17dcced02b0fedf440
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/501873
diff --git a/third_party/pigweed b/third_party/pigweed
index 06cf2cf..414050b 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 06cf2cf0cb4d5cf40f1aa46bdb254744f8c3f1ce
+Subproject commit 414050ba2a04f9e337971ee1664f92bbd0511838