Refactor metrics implementation

[srijan-27]

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.