feat: add inverse_transform() to steps

[jitingxu1]

Transform processed data back to original feature space.

Note that some transformations cannot be converted to the original value.

Reference:

• minMax inverse_transform
• tidymodels - step_inverse()

[deepyaman]

@lostmygithubaccount marking this as P1 for now; if you think it's absolutely critical for release, let's bump to P0.