Add config and flag check to getEmergencyCallToSatelliteHandoverType()

to get the handover type from the carrier config.

Flag: com.android.internal.telephony.flags.carrier_roaming_nb_iot_ntn

Test: cts: atest CarrierConfigManagerTest
Manual Test: b/348385869
Bug: 350397936

Change-Id: I3debd980ca74db28df097854c5397dd735c9e1b3