Move some utility methods to MdnsUtils

Bug: 265787401
Test: atest FrameworksNetTests
(cherry picked from https://android-review.googlesource.com/q/commit:5fffb2d96022eab667f822c06c7acf7ee2d24b83)
Merged-In: I92ba54809c2b291fd1f176fbda80a347f5944288
Change-Id: I92ba54809c2b291fd1f176fbda80a347f5944288
7 files changed