Move DhcpInfoTest to frameworks/base/tests/net/common

Address comment from aosp/1162443.
Move to FrameworksNetCommonTests so that it can be run in
cts test and presubmit test.

Also change package name from android.net.cts to android.net

Bug: 154299158
Test: atest FrameworksNetTest
      atest CtsNetTestCasesLatestSdk:android.net.DhcpInfoTest
Change-Id: I42a965ae5cb748fdd80b4d5c0f8b26f36f74be72