IMS: Use proper phone to route emergency calls

-- By default emergency calls will be dialed using ImsPhone.
   For multi-sim use cases if tried to dial emergency calls
   using ImsPhone where feature state is NOT_READY then will
   end up in not sending DIAL request to lower layers as
   ImsServiceProxy will not allow creating call profile if
   feature state is NOT_READY.
-- Check feature state before routing emergency calls to ImsPhone.

Test: Manual
Bug: 63920021
Change-Id: Ie74a4a368b860d9ad284cef6b90a2cc7eff19609