Support RRO for emergency number conversion map

With current implementation, configurable emergency call number map is
read from global shared resources object that provides access to only
system resources(no application resources).
It means RRO(runtime resource overlay) is NOT supported.

This patch also applies refactoring to remove function
isConvertToEmergencyNumberEnabled.

Bug: 37762325
Test: Manual
Change-Id: Ib1672fabbb77880c89f31bf1661b4690e5c8a064