Refactor metrics implementation

Extension of #529
- A new counter metric needs to be added which represents server errors (`app_server_error`)
- A new counter metric for circuit open counts (`app_circuit_open_count`)

Current metrics implementation makes it harder to use in different packages as it requires an instance of metricsManager everywhere, need to think of a better solution and implement in such a way that a copy of metricsManager should not be required to pass everywhere.

Start with the current metrics implementation and issue #529, then trace how metricsManager is passed across packages. Define the approach for shared metric access, add the app_server_error and app_circuit_open_count counters, and verify that callers no longer need to pass a copy of metricsManager everywhere.

Written by the indexing model from the issue text.