dotnet-trace doesn't provide feedback when the end of collection process has begun

[acolombi]

When the user presses "Enter" to end collection, dotnet-trace doesn't indicate it's received the event. I was in an environment where the shutdown sequence was slower than usual, and I actually thought dotnet-trace wasn't receiving the "Enter" command. In my development environment it only took a few seconds between pressing "Enter" and getting confirmation that the profile was complete. In this environment it took 1 minute. It took me awhile to realize it was just slow, and not ignoring my request.

I recommend giving some output so the user knows dotnet-trace has entered its shutdown phase and is wrapping things up.

[sywhang]

Thanks for the great feedback @acolombi!