VF debugging info and progress callbacks, and mesh recon progress callbacks

[ebrahimebrahim]

• Splits out skin mesh computation from virtual fit function to its own function compute_skin_mesh_from_volume. Allow skin mesh to optionally be . This is what @sadhana-r had already done (before my interruption 😁), and is needed for SlicerOpenLIFU#195.
• Adds an option to return a packet of debugging info VirtualFitDebugInfo.
• Adds an option to include a progress callback in both the virtual fitting and the mesh reconstruction.

For Review

• A cursory look over the code is sufficient. Each commit does something quite different so it will be easier to look at the commits one by one. The only one to look at carefully is the first commit, the one that splits out the skin mesh computation, since you will immediately need to use that.
• The easiest way to review functionality is to try out the companion SlicerOpenLIFU PR: VF debugging utilities, VF transform bug fix, Mesh recon controls, and VF and mesh recon progress bars SlicerOpenLIFU#381

[ebrahimebrahim]

@dlichy only adding you for visibility since this touches the run_reconstruction function; feel free to comment if you have any comments, but no need to review

[sadhana-r]

Looked over the code and tested as part of OpenwaterHealth/SlicerOpenLIFU#381. Changed looks good to me!