Merge "Add method to get all valid prefixes in PrefixDelegation class." into main am: f1feca062f am: b9692a5498

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

Change-Id: I26a06a2950b538f2c1a94cbaafb38f160a657158
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>