Make ange-ftp fit for tramp-tests

Make ange-ftp fit for tramp-tests

* lisp/net/ange-ftp.el (ange-ftp-repaint-minibuffer): Use empty message.
(ange-ftp-quote-string): Unquote the string.
(ange-ftp-substitute-in-file-name, ange-ftp-access-file)
(ange-ftp-copy-directory, ange-ftp-make-symbolic-link)
(ange-ftp-add-name-to-file): New defuns.  Set 'ange-ftp property.
(ange-ftp-real-substitute-in-file-name)
(ange-ftp-real-copy-directory): New defuns.
(ange-ftp-file-name-as-directory): Care about `non-essential'.
(ange-ftp-file-attributes): Handle ID-STRING.
(ange-ftp-copy-file-internal, ange-ftp-rename-file)
(ange-ftp-make-directory): Improve error handling.
(ange-ftp-insert-directory): Initialize SWITCHES if they are nil.

* test/lisp/net/tramp-tests.el (ange-ftp-make-backup-files): Declare.
(tramp-test39-make-nearby-temp-file, tramp--test-ange-ftp-p): New defun.
(tramp-test05-expand-file-name-relative)
(tramp-test06-directory-file-name, tramp-test10-write-region)
(tramp-test11-copy-file, tramp-test12-rename-file)
(tramp-test17-insert-directory)
(tramp-test26-file-name-completion)
(tramp-test37-make-auto-save-file-name)
(tramp-test38-find-backup-file-name)
(tramp--test-special-characters): Use it.