1/n: Rename BiometricService to BiometricServiceBase

This is in preparation for BiometricManager. This file is actually the
base class of <Biometric>Service, and isn't itself a system service,
since BiometricManager should follow the Manager/Service pattern.

Bug: 112570477

Test: Builds
Change-Id: I1287681a470de1634893188f5e8727604f2398ee