Move common device metrics code to InputDeviceMetricsSource

Move common device metrics code from InputDeviceMetricsCollector to
InputDeviceMetricsSource.
The common code moved is:
* enum class InputDeviceUsageSource
* InputDeviceUsageSource getUsageSourceForKeyArgs(int32_t, const NotifyKeyArgs&)
* set<InputDeviceUsageSource> getUsageSourcesForMotionArgs(const NotifyMotionArgs&)

This code will be used by both InputDeviceMetricsCollector,
which is a part of inputflinger as well as LatencyTracker,
which is a part of the dispatcher.
InputDeviceMetricsSource can be included in the places using the common code.

Bug: 303059859
Test: atest inputflinger_tests:InputDeviceMetricsSourceDeviceClassificationTest
Change-Id: Ia8528e641cd162d5025495d5bf6903b2dbab2ed3