Add a final lux method to ALSProbe.

This address two remaining issues with with ALS logging since the pointer events were removed from the framework (starting at commit aa07cc3d).

1) After the pointer events were removed the logging was updated to use wakefullness events as an alternative trigger. However, these events are often too slow when authenticating from the AoD and the sensor may not have a chance to be enabled or respond before the operation completes. The new method allows the sensor to be enabled after the operation has completed to fetch a value.
2) Fixes a bug where the initial wakefullness status was not checked at the start of an auth operation.

Fix: 253318983
Test: atest ALSProbeTest FingerprintAuthenticationClientTest BiometricLoggerTest
Test: statsd_testdrive 88 (verify lux field is always greater than 0 from AoD and with BP test app)
Change-Id: I2b1572579f52dc9dad7238d47e27b0068c7c74c6