Ringtone: Add support for selection of phone ringtone for SIM-2.

-Issue: "The process android.process.media has stopped" pop up is
 displayed when ringtone for SIM-2 is selected.
-Rootcause: There is no type and URI defined for SIM-2 ringtone
 in the RingtoneManager. This is leading to SQl exception when
 executing a selection query.
-Fix: Add URIs for the SIM-2 and SIM-3 ringtones. Define
 interfaces to return them to app side based on subscription ID.

CRs-Fixed: 612945
Change-Id: If68c2d008dd86d2b55d3fb7f5667bbadc238d0b3
Provider: Add multi SIM ringtone support in SettingsProvider

This change will handle multi-sim queries in
SettingsProvider.java when openFile and
openAssetFile APIs are called by other components.
Thus, it will ensure to play the correct ringtone
corresponding to the SIM.

CRs-Fixed: 661216
Change-Id: I7b22c233b9c41669c1ad948b83a7aa2c55442af1