Add MDnsManager am: 541b72d03b

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2049244

Change-Id: I5c73fb532fcd5e6cc8e258992fa06475480e601a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>