Log windows that are being interacted with

If the list of windows being interacted with changes, log the new list
to event log.

Example logs:

06-08 15:47:55.349  4105  4181 I input_interaction: Interaction with windows: ee638df NotificationShade (server),
06-08 15:48:03.917  4105  4181 I input_interaction: Interaction with windows: 399b259 com.google.android.apps.nexuslauncher/com.google.android.apps.nexuslauncher.NexusLauncherActivity (server),
06-08 15:48:10.844  4105  4181 I input_interaction: Interaction with windows: fcc1e60 com.android.systemui.ImageWallpaper (server), 399b259 com.google.android.apps.nexuslauncher/com.google.android.apps.nexuslauncher.NexusLauncherActivity (server),
06-08 15:49:30.091  4105  4181 I input_interaction: Interaction with windows: ee638df NotificationShade (server),
06-08 15:49:31.757  4105  4181 I input_interaction: Interaction with windows: fcc1e60 com.android.systemui.ImageWallpaper (server), 399b259 com.google.android.apps.nexuslauncher/com.google.android.apps.nexuslauncher.NexusLauncherActivity (server),
06-08 15:49:33.293  4105  4181 I input_interaction: Interaction with windows: <none>

Bug: 153092301
Test: adb logcat -b events | grep -i input
Change-Id: Ia4216beb200163e60e05374b6ea363412bff55f3
Merged-In: Ia4216beb200163e60e05374b6ea363412bff55f3