What should `affirm_class()` return in the report?

[ddsjoberg]

Currently, the report would contain the columns that do not inherit the intended class with all rows from the original data frame.

Perhaps it would be better to return a tibble like this:

column	class	expected_class
am	numeric	character
mpg	character	factor

Since a column can have multiple classes, we'd need to include a paste(cls_vector, collapse = ', ')