Blame services for slow operations

The system will now log a warning if a service takes 50+ ms to handle
a lifecycle callback.

Example:
SystemServiceManager: Service class com.android.server.appwidget.AppWidgetService took 404 ms in onUnlockUser

Test: device boots, times are logged
Bug: 37579992
Change-Id: Id1f339d02e1854f3a9acf85eb54b03f35ff68b89