Make CpuPowerCalculator's Estimators available to com.android.internal

BatteryStats needs the power_profile Cpu constants to smear the measured
CPU Cluster energies across UIDs. Using the CpuPowerProfileCalculator to
get the calculation decreases the chance of someone accidentally
diverging estimated and measured CPU power calculations.

Bug: 180079165
Test: tbd
Change-Id: I474cd019d177bd07f2ae48a47b83a82e4074ed4f