Add DPM API to block apps from using metered data.

Bug: 63700027
Test: cts-tradefed run singleCommand cts-dev -m CtsDevicePolicyManagerTestCases -t \
      com.android.cts.devicepolicy.MixedDeviceOwnerTest#testSetMeteredDataDisabled
Test: cts-tradefed run singleCommand cts-dev -m CtsDevicePolicyManagerTestCases -t \
      com.android.cts.devicepolicy.MixedProfileOwnerTest#testSetMeteredDataDisabled
Test: atest com.android.server.devicepolicy.DevicePolicyManagerTest#testSetGetMeteredDataDisabled
Change-Id: I147399d316f375c68b415dc6ede837c53cd1aad0