[automerge] Move some utility methods to MdnsUtils 2p: 64732f379f

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/23074355

Bug: 265787401
Change-Id: I5d7ca5b7278850fbb0538f54faf6cbe7acd53c9e
Merged-In: I92ba54809c2b291fd1f176fbda80a347f5944288