Refactor ZIO OTEL metrics to use ConcurrentMetricRegistry

[ptrdom]

Our current approach to instrumenting ZIO metrics breaks if their mapping functions are used. A better approach would be to interact directly with ConcurrentMetricRegistry. It does provide two approaches - pull based snapshots and push based listeners. Currently push based 'listeners' have at least one issue with them that makes them non-ideal to use - see zio/zio#7897 (comment). We should implement pull based snapshots approach now, maybe consider implementing push based listeners approach in the future and allow users of the Mesmer to toggle which one they want to use.

Should resolve #629 and #423.

[ptrdom]

Seems like there is no implementation yet for synchronous gauge - open-telemetry/opentelemetry-specification#2318.