Add coordinate system declaration to fiber bundle files

[pieper]

In newer Slicer versions, files that don't explicitly declare one or the other, files are assumed to be LPS. But FiberBundles are RAS, when read in Slicer as models they are in the wrong space.

The WMA code should add a string array field like this one here to declare the coordinate system:

https://github.com/SlicerDMRI/SlicerDMRI/blob/master/Modules/Loadable/TractographyDisplay/MRML/vtkMRMLFiberBundleStorageNode.cxx#L28

In Slicer this is done by making setting the flag about the coordinate system at the MRML level:
https://github.com/Slicer/Slicer/blob/main/Libs/MRML/Core/vtkMRMLModelStorageNode.cxx#L581-L586

So the WMA code should be updated to match since sometimes it's useful to load fiberbundles as models.