Settings: Add a shortcut icon for carrier selection

* This is a re-implementation from cm-13.0
* The new implementation pop ups a SIM chooser in case of
  multisim and opens the network operator selection for the
  selected sim rather than the first one
* In case of single-sim it directly opens the network operator
  selection for the sim

Change-Id: Iad7f43b3e56449432fe009bf44d68d703768981e