Copy tables to same source, if necessary

Usage

auto_copy(x, y, copy = FALSE, ...)

x, y: y will be copied to x, if necessary.
copy: If x and y are not from the same data source, and copy is TRUE, then y will be copied into the same src as x. This allows you to join tables across srcs, but it is a potentially expensive operation so you must opt into it.
...: Other arguments passed on to methods.