Implement `tune::last_fit()`

[JavOrraca]

In situations where a model was trained via hyperparameter tuning and finalized / re-fit with tune::last_fit(), I encounter the following error:

Error in `orbital()`:
! Is not implemented for a <last_fit> object.

This {orbital} implementation would be excellent, and I'm loving this early stage package! 🚀

Two other observations and questions:

• I don't see a binding for recipes::step_dummy() in the package - Is this in the works?
• Will any {embed} functions be implemented with this? For example, embed::step_lencode_mixed() or embed::step_lencode_glm() (although, I fully recognize this would be a bear) 🙏

[JavOrraca]

Note: This would require support for rsample::initial_split() objects, etc.

[EmilHvitfeldt]

I have a handful of steps that will be able to be translated, step_dummy is on the list, as are many of the embed steps