[3.12] pythonGH-89727: Fix shutil.rmtree() recursion error on deep trees (pythonGH-119808)

Implement `shutil._rmtree_safe_fd()` using a list as a stack to avoid emitting recursion errors on deeply nested trees.

`shutil._rmtree_unsafe()` was fixed in a150679..
(cherry picked from commit 53b1981)

Co-authored-by: Barney Gale <[email protected]>

Author: barneygale