Add new carrier config key for calls answered elsewhere.

Adding support for configuring whether a carrier wants to log "calls answered elsewhere" in the call log.  This applies for multiendpoint type solutions where a call rings on multiple devices at the same time.

Test: Added CTS test overage for this functionality.
Flag: com.android.internal.telephony.flags.log_calls_answered_elsewhere
Bug: 405460896
Bug: 432782589
Change-Id: If1cd9012450f2ab109bb77411df3ac18a2a477f2