Implement function to calculate metrics from EvaluationResult

[silvanocerza]

As specified in proposal #5794 we need to implement the calculate_metrics() function.

The calculated_metrics() function will expect this arguments:

• evaluation_result: EvaluationResult
• metric: Union[Metric, MetricCalculator]
• **kwargs

And will return an instance of MetricsResult.

Metric can be either a simple Enum or a Literal. Probably an Enum will ease the discoverability of supported metrics.
MetricCalculator will be a Callable[..., MetricResult].
**kwargs will be passed to the function used to calculate the metrics, can be obviously omitted.

For more detailed information check out the original proposal.