Add more available metric in the report

[glemaitre]

Right now, we have a subset of metric available in the report (the class). I get the point to not expose all metric when calling report_metrics but I think that we should expose more mainstream metrics like MAE, MedAE, MAPE, etc.

[sylvaincom]

You mean making more metrics available in the EstimatorReport's help tree but not in the report_metrics pandas dataframe?

[glemaitre]

the report_metrics pandas dataframe

Yes we need to be more editorial there. For instance, MAPE with zero values should not be used, etc.

So we could revisit the default metric.