Add middleware that prints stacktraces to gitaly-ruby
In development and test, it would be useful if gitaly-ruby exceptions printed a stacktrace. Just like you see in Rails log output.
I'm not sure if we want it in production because there we have Sentry already. Maybe we should have the stacktrace printer off by default, with an environment variable to turn it on.
This would be a GRPC middleare in gitaly-ruby.