Add the link capacity estimate system API.
Remove the system API of getCarrierBandwidth() and CarrierBandwidth as
they are replaced by the new LCE system API in PhoneStateListener.
Bug: 180434672
Bug: 176814680
Test: manual test of the new LCE system API in LinkBandwidthEstimator
Test: atest -c PhoneStateListenerTest
Merged-In: I5899acf02006a164e31f9b82aeaa7974dd6d2869
Change-Id: I5899acf02006a164e31f9b82aeaa7974dd6d2869