Support for more loggers in apm.start

**Is your feature request related to a problem? Please describe.**
All of my applications use Winston for logging and I would like to be able to combine the output from elastic-apm-node into my normal log stream output so that I do not miss any errors reported there.

**Describe the solution you'd like**
Implement logging in a more abstract way so that users can use Pino, Winston, Log4js or other popular logging libraries

**Describe alternatives you've considered**
I tried to map the winston logger interface to emulate Pino with no success