SystemUI: Redesign the scheme of selecting icons on signal cluster

1. Define icons arrays in res/values/arrays.xml, e.g. arrays for
   signal strength, data type, data activity, etc., so that these
   arrays are able to be overlayed.
2. Enhance TelephonyIcons.java, get the arrays defined in arrays.xml,
   and provide APIs to get icons.
3. Using new interface to get icons inside NetworkController and
   MSimNetworkController.

CRs-Fixed: 627830

Change-Id: I5e735a43a7448a658dc621b24fffb29f56c133f9