Unify metric names in ApiMetric & MetricsRepository

[MorrisNein]

Currently, when a user passes a metric name to FEDOT API, the ApiMetric maps the name to the function.

ApiMetric contains its own map from metric names to metric implementations that does not correspond to the inner MetricsRepository.

This leads to different metric names in API ("acc" instead of "accuracy") or inability to use some metrics by their names (such as "precision")

Therefore, ApiMetric should use MetricsRepository instead of its own map.