[FEATURE] Add an API to provide signed distance maps

[tvercaut]

Is your feature request related to a problem? Please describe. In several applications, having a signed distance map is helpful.

Describe the solution you'd like Providing a simple API to get signed distance maps in FastGeodis would be great.

Describe alternatives you've considered Compute two distance maps (one with the mask and another one with the inverted mask) and substract these

Additional context https://github.com/Project-MONAI/MONAI/discussions/4603

[masadcv]

Would this be equivalent to getting the output of these functions?

https://github.com/masadcv/FastGeodis/blob/d61aac07dd2323123a3c7195c512ba83c4b90dc5/FastGeodis/fastgeodis.cpp#L147-L153

and

https://github.com/masadcv/FastGeodis/blob/d61aac07dd2323123a3c7195c512ba83c4b90dc5/FastGeodis/fastgeodis.cpp#L168-L174

I can expose them through pytorch + python headers..

[tvercaut]

Nice. Yes, that looks right. I assume there might be a way to optimise things by running the raster scans with mask and 1-mask in parallel but this can be left for future improvements.

[masadcv]

Makes sense, yes let's look into it in future improvements!

[masadcv]

Closing this for now as it is addressed in #10 - we can reopen/look into improving this in future