Rearrange argument handling in Tramp scp calls.

Rearrange argument handling in Tramp scp calls.

* lisp/net/tramp-sh.el (tramp-do-copy-or-rename-file-out-of-band):
Use `start-process' instead of `start-process-shell-command'.
(tramp-make-copy-program-file-name): Do not quote `localname'.

* test/lisp/net/tramp-tests.el (tramp-method-out-of-band-p): Declare.
(tramp--test-windows-nt-and-batch-p)
(tramp--test-windows-nt-and-pscp-psftp-p): Remove, and also all callees.
(tramp--test-windows-nt-and-out-of-band-p)
(tramp--test-windows-nt-and-scp-p): New defuns.
(tramp-test17-dired-with-wildcards)
(tramp-test40-special-characters)
(tramp-test40-special-characters-with-stat)
(tramp-test40-special-characters-with-perl)
(tramp-test40-special-characters-with-ls, tramp-test41-utf8)
(tramp-test41-utf8-with-stat, tramp-test41-utf8-with-perl)
(tramp-test41-utf8-with-ls): Use them.