[ENH] Refactor dental segmentator logic for standalone processing

[Thibault-Pelletier]

Describe the solution you'd like

Implement a dental segmentator logic class to be able to use the logic other modules.

Additional context

Currently, some logic steps are done in the widget and are not easy to reuse without reimplementation in other modules.

[mauigna06]

May be useful:
https://github.com/SlicerIGT/SlicerBoneReconstructionPlanner/blob/newMain/BoneReconstructionPlanner/BRPLib/DentalSegmentatorHelper.py

https://github.com/SlicerIGT/SlicerBoneReconstructionPlanner/blob/534a777f2aabbf447c98fa5f1239b0c53a11c794/BoneReconstructionPlanner/BoneReconstructionPlanner.py#L2150-L2154

https://github.com/SlicerIGT/SlicerBoneReconstructionPlanner/blob/534a777f2aabbf447c98fa5f1239b0c53a11c794/BoneReconstructionPlanner/BoneReconstructionPlanner.py#L2167-L2192

[Thibault-Pelletier]

Thx @mauigna06 for the code snippet!