Add test case for getNetworkSlicingConfiguration() Bug: 178075247 Test: run "atest TelephonyManagerTest#testGetNetworkSlicingConfiguration" [1/1] android.telephony.cts.TelephonyManagerTest#testGetNetworkSlicingConfiguration: PASSED (2ms) Change-Id: Ia02d92b28a7bb8c8e171ce05177debed045a1570