split: deprecate keep option in favor of filtering #20628
Description
The keep option to split, in addition to being somewhat unfortunately named (probably my doing if we excavate), is kind of strange since we can accomplish the same thing by writing filter(!isempty, split(str, splitter)). If we had a generator version of split then this could even be just as efficient as split(str, splitter, keep=false).
Related: #20625