Task: add additional interpolation methods

[tamsinrogers]

for volumetric transform

currently:

• gaussian, bSpline, multiLabel - not currently supported by niwrap
• interpolation methods that require additional parameters give TypeError: string indices must be integers, not 'str' (see [Descriptor Issue]: antsApplyTransforms bspline interpolation styx-api/niwrap#263)

[kaitj]

With #47, only thing that should still need to be implemented is bSpline