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.
1 job for master in 56 minutes and 48 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #4138
test-all

00:56:48

 
Name Stage Failure
failed
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make[2]: *** [check-doit] Error 1
make[1]: *** [check-expensive] Error 2
make: *** [check-expensive] Error 2
Makefile:959: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1