Add some new modality-specific APIs in BiometricManager.

- getEnrolledFingerprintCount()
- getEnrolledFingerprintCount()

Bug: 399438509
Test: atest AuthServiceTest
Test: atest BiometricSimpleTests
Flag: android.hardware.biometrics.move_fm_api_to_bm

Change-Id: I8bdc8fdf965e65d1ecd3ed34fe469d4f7c7f3201