Port the "Normal" and "Curve Tangent" nodes to the new curves data-block
to avoid the conversion to `CurveEval`. This should make them faster by
avoiding all that copying, but otherwise nothing else has changed.
This also includes a fix to move the normal mode as a built-in curve
attribute when converting to and from `CurveEval`. The attribute is
needed because the option is used implicitly in many nodes currently.
Differential Revision: https://developer.blender.org/D14609
