Merge "Add method to get all valid prefixes in PrefixDelegation class." into main am: f1feca062f

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/2786161

Change-Id: I94de88fa6bab9edd61463b14ad625c81a0e200d0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>