This adds an @trace annotation for tracing functions. Code was mostly copied from the New Relic Elixir agent also licensed under Apache License 2.0. I assume this is better code than I can come up with that's already used in production, but I'm willing to rewrite / re architect as needed. I wasn't sure if / how you wanted tests considering there are none for the Elixir code. #elixir #opentelemetry