A fit is learned on the columns decom@config@features names, so only those
columns of new_data are transformed; the remaining columns are returned
unchanged, alongside the learned components, in the layout
[kept features, components]. decomp() resolves an unset features to
the numeric columns and records them, so a fit it produced always names
them. A Decomposition assembled by hand with no features transforms
every column of new_data and returns only the components.
Available for algorithms whose can_apply trait is TRUE; see
decomposition_traits. transformed() returns the components of the data
the decomposition was fitted on.