Implementation of boundary-aware shape loss

[arnauddhaene]

Is your feature request related to a problem? Please describe. I would like to have the shape-aware loss from Huang et al., 2021 implemented in MONAI.

Describe the solution you'd like I would like to have something like a ShapeLoss class that implements the loss described in the paper or a variation of it.

Describe alternatives you've considered I've implemented it myself, and am creating this issue to link it to my PR.

Additional context N.A.