Merge "Add mdns files and unit tests" am: 57852487b8

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2098221

Change-Id: If638a86e3cbcb8c4f66d5edb0616b06f809663c4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>