Add commandline option to update power-save-except-idle whitelist.

Bug: 37670935
Test: manual &&
      cts-tradefed run singleCommand cts-dev -m CtsHostsideNetworkTests -t \
      com.android.cts.net.HostsideRestrictBackgroundNetworkTests
Change-Id: Iad866a3ea4908fdf7d341d8607e8dbc8b1139d60