animate_join() now lives in animate_join.R with the other animate_join_ functions. These all use rlang::enquo() to capture their arguments so that animate_join() can print the variable name in the plot title.

if printed it will still call animate, but gives the user more flexibility about animation factors (such as times etc)

this makes it easier to differentiate between the join-related and the (coming) tidyr-related functions that have similar goals