Add ConnectivitySettingsManagerTest

- Add tests for ConnectivitySettingsManager.
- Also address leftover javadoc comments.

Bug: 182538166
Test: atest FrameworksNetTests
Test: atest CtsNetTestCases
Original-Change: https://android-review.googlesource.com/1738353
Merged-In: I8161c1bca84b41964578d59ee5d6ab07b2380707
Change-Id: I8161c1bca84b41964578d59ee5d6ab07b2380707
2 files changed