Implement MASE Loss

[qsimeon]

Do a proper working and differentiable implementation of the MASE loss
See here: scikit-learn/scikit-learn#18685
And also see Pytorch implementation for MAE and MSE:

• https://pytorch.org/docs/stable/generated/torch.nn.L1Loss.html
• https://pytorch.org/docs/stable/generated/torch.nn.MSELoss.html

Also check out implementation in sktime:

• https://github.com/sktime/sktime/blob/ee7a06843a44f4aaec7582d847e36073a9ab0566/sktime/performance_metrics/forecasting/_functions.py#L16