Added Ble scan APIs to BatteryStatsManager

Added missing service functions to manager to prevent directly
calling BatteryStatsService from Bluetooth package. Updated
system-current.txt accordingly.

Tag: #feature
Bug: 190442794
Test: Manual
Merged-in: Ie6c6d3688d2da45956d57ea1dbc2cc4430f27783
Change-Id: Ie6c6d3688d2da45956d57ea1dbc2cc4430f27783