bpo-41490: ``path`` and ``contents`` to aggressively close handles (#22915)

* bpo-41490: ``path`` method to aggressively close handles

* Add blurb

* In ZipReader.contents, eagerly evaluate the contents to release references to the zipfile.

* Instead use _ensure_sequence to ensure any iterable from a reader is eagerly converted to a list if it's not already a sequence.