Predictions / Test & Score: MAPE of linear regression in evaluation results (similar to #6975)

[wvdvegte]

What's your use case?
In addition to the F-test (#6975), it would also be useful to include the mean average percentage error of regression in Predictions and Test & Score. It is similar to the MAE but it is relative and therefore easier to interpret. It would also be easy to implement.
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Are there any alternative solutions?
Use a formula APE := 100 * abs((target - Linear_Regression)/target) and use Feature statistics to calculate the mean.