This commit makes the NsdManager.registerService() API public. This
change will enable developers to implement more customizable mDNS
advertising behavior in their applications.
Bug: 373270045
Test: atest CtsNetTestCases:NsdManagerTest
Flag: com.android.net.flags.mdns_advertising_improvement
API-Coverage-Bug: 415202964
Change-Id: I32359f7265b3597defd57123ecff0deaef0011f8