Bezier splines have the option of different interpolation methods between control points.
To achieve feature parity with the old curve implementation, these should be supported
for geometry nodes curves as well.
{F11838239 size=full}
Because of the generalized way attributes are handled in geometry nodes, supporting
a different interpolation method for the `tilt` and `radius` is much more complicated,
and would require special cases in many areas of the code. I propose merging the two
options, so a spline can only have one interpolation method that applies to all attributes.
If one wants to interpolate tilt and radius differently, it would always be possible by changing
the interpolation mode procedurally and capturing the result as an anonymous attribute.