CTS test for setOemNetworkPreference permissions

CTS test verifying that setOemNetworkPreference() can only be called
with the requisite permissions. Also updating the test to work with
junit4 so that we can use `assume`.

Bug: 176496580
Bug: 176494815
Test: atest phone CtsPermissionTestCases:
android.permission.cts.ConnectivityManagerPermissionTest

Change-Id: I49231773a813ec2edb9b5b96cc07417981e9d183
1 file changed