Rework file notifications, kqueue has problems with directory monitors

Rework file notifications, kqueue has problems with directory monitors

* lisp/filenotify.el (file-notify-add-watch): Call the native
add-watch function on the file, not on the dir.

* src/kqueue.c (kqueue_compare_dir_list): Make also bookkeeping
about already deleted entries.

* test/automated/auto-revert-tests.el
(auto-revert-test01-auto-revert-several-files): Do not call "cp -f"
since this deletes the target file first.

* test/automated/file-notify-tests.el (file-notify--test-event-test):
Make stronger checks.
(file-notify-test01-add-watch, file-notify-test02-events)
(file-notify-test04-file-validity, file-notify-test05-dir-validity):
Rewrite in order to call file monitors but directory monitors.
(file-notify-test06-many-events): Ler rename work in both directions.