[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

Merged-In: Ie66e13c85467a7bd59db52933c1e8f6a7cb93a75
Change-Id: Ie66e13c85467a7bd59db52933c1e8f6a7cb93a75