Provide a no-dependency `Metrics` class implementation

[metacosm]

We should separate the Metrics class from micrometer so that users who are not interested in monitoring don't carry the dependency. This would mean creating a separate module for the micrometer-based implementation.

[csviri]

I'm just wondering if this is worth it. I mean what we get when we don't have micrometer core on classpath? It's true that is has bunch of dependencies what is not nice.
An mainly taking in mind that such metrics are essential to monitor in a production system. So user should end up using it anyways.

[csviri]

Also thinking is we could trick this without a new module, if somebody is not using it. So build it with "provided" dependency, but if somebody will jus tset an empty metric class with not dependency on actual micrometer, it could work. Not sure though.