CTS tests for DPM.listForegroundAffiliatedUsers(). Bug: 173541467 Bug: 179163496 Test: atest CtsDevicePolicyManagerTestCases:com.android.cts.devicepolicy.DeviceOwnerTest#testListForegroundAffiliatedUsers_onlyForegroundUser,testListForegroundAffiliatedUsers_extraUser,testListForegroundAffiliatedUsers_notDeviceOwner,testListForegroundAffiliatedUsers_notAffiliated,testListForegroundAffiliatedUsers_affiliated Change-Id: I520dc35da627d7cb89f6ff2d7010fc04af1b01f7