[Telephony] Notify onLinkCapacityEstimateChanged

Add the implementation of onLinkCapacityEstimateChanged().
Remove the implementation of getCarrierBandwidth() as it is replaced by
the new LCE callback.
LinkCapacityEstimate is now moved to framework/base as a new system API interface.

Bug: 176814680
Test: atest CtsTelephonyTestCases:PhoneStateListenerTest
Change-Id: If7cede0f48b557d840ee06120d34c80e1c7b4bc6