Add Tramp sshfs method

Add Tramp sshfs method

* doc/misc/tramp.texi (Top, Configuration): Insert sections 'FUSE-based
methods' and 'FUSE setup' in menu.
(Quick Start Guide): Fix @anchors.  Add doas.  Extend section
'Using @command{rclone}' to 'Using @acronym{FUSE}-based methods'.
(External methods): Remove rclone paragraph.
(FUSE-based methods, FUSE setup): New nodes.
(Predefined connection information): Mention "mount-point".

* etc/NEWS: Mention Tramp sshfs method.
Fix typos and other oddities.

* lisp/net/tramp-fuse.el: New file.

* lisp/net/tramp-rclone.el (tramp-fuse): Require.
(tramp-rclone-file-name-handler-alist): Replace `tramp-rclone-handle-*'
by `tramp-fuse-handle-*' where appropriate.
(tramp-rclone-handle-delete-directory)
(tramp-rclone-handle-delete-file)
(tramp-rclone-handle-directory-files)
(tramp-rclone-handle-file-attributes)
(tramp-rclone-handle-file-executable-p)
(tramp-rclone-handle-file-name-all-completions)
(tramp-rclone-handle-file-readable-p)
(tramp-rclone-handle-insert-directory)
(tramp-rclone-handle-insert-file-contents)
(tramp-rclone-handle-make-directory, tramp-rclone-mount-point)
(tramp-rclone-mounted-p, tramp-rclone-local-file-name):
Remove.  Functionality moved to tramp-fuse.el.
(tramp-rclone-remote-file-name)
(tramp-rclone-maybe-open-connection): Use `tramp-fuse-*' functions.

* lisp/net/tramp-sh.el (tramp-do-copy-or-rename-file-out-of-band):
Simplify check.

* lisp/net/tramp-sshfs.el: New file.

* lisp/net/tramp.el: Remove TODO item.

* test/lisp/net/tramp-tests.el (tramp--test-sshfs-p): New defun.
(tramp-test14-delete-directory): Use it.