It is still there as a widget, not an app.
You might Trying doing a Google Search and See if it's listed in either the Lollipop Quick start Guide or the Lollipop Manual..
No app, no widget. It was supposed to be there according to Lollipop documentation but does not exist.
All you have to do is click on the microphone in google search and say flashlight on. That's it. Or just say Ok Google flashlight on.