add more loss function options

[PhilipMay]

Add more options to the non default loss functions.
This is distance_metric and margin.
The default values are selected in a way that this is no breaking change.

Todo

• add docstrings

[PhilipMay]

CI is green, this is done and can be merged from my point of view.

[lewtun]

Thanks for adding these additional args @PhilipMay 🤗 !

I think at some point we'll need to refactor this out to a dedicated class for the training args (like the transformers.Trainer), but happy to have this included for now :)

[PhilipMay]

Thanks for adding these additional args @PhilipMay 🤗 !

I think at some point we'll need to refactor this out to a dedicated class for the training args (like the transformers.Trainer), but happy to have this included for now :)

Should we collect this "future ideas" anywhere?