File notifications report unmount events (bug#66381)

File notifications report unmount events (bug#66381)

* doc/lispref/os.texi (File Notifications): Unmounting a watched
filesystem is reported now.

* etc/NEWS: File notifications report unmount events now.
Fix typos.

* lisp/filenotify.el (file-notify--callback-inotify)
(file-notify--add-watch-inotify): Handle `unmount'.
(file-notify--callback-kqueue, file-notify--add-watch-kqueue):
Handle `revoke'.
(file-notify--callback-gfilenotify): Handle `unmounted'.
(file-notify-callback): Handle `unmount' and `unmounted'.
(file-notify--add-watch-inotify):

* lisp/net/tramp-gvfs.el (tramp-gvfs-handle-file-notify-add-watch):
Handle `unmounted'.

* lisp/net/tramp-sh.el (tramp-sh-handle-file-notify-add-watch):
Handle `unmount' and `unmounted'.

* src/gfilenotify.c (dir_monitor_callback): Handle Qunmounted.

* src/inotify.c (symbol_to_inotifymask): Handle IN_IGNORED and
IN_UNMOUNT.

* src/kqueue.c (kqueue_callback, Fkqueue_add_watch):
Handle NOTE_REVOKE.
(Fkqueue_add_watch): Adapt docstring.
(syms_of_kqueue): Declare `revoke.