Reduce required third-party dependencies for Phileas core by removing `phileas-metrics-service` about phileas

[jzonthemtn]

@RobDickinson Thanks for typing this up. Agreed that Phileas should be more lighter weight. I will take this one on since it might involve moving the metrics stuff out into its own GitHub repository to simplify the code and make it more loosely connected.

[jzonthemtn]

Because Phileas is a library to do redaction, it has to be used from within another application. I don't think it is necessary for Phileas to have an integrated implementation of MetricsService when the application implementer can easily add their own metric collection and have more flexibility when doing so.

The phileas-metrics-service will be removed from Phileas and integrated with Philter so the functionality can still be used, but Phileas will now let users their own implementation of MetricsService.

This however does not address the issue of the size of the jar file. The ONNX Runtime dependencies are responsible for a very large part of the 270 MB jar file.

Wrote #134 to take a better look at the size of the dependencies.