Make Tramp scripts more unique and robust

Make Tramp scripts more unique and robust

* lisp/net/tramp-sh.el (tramp-uudecode, tramp-perl-file-truename)
(tramp-perl-file-name-all-completions)
(tramp-perl-file-attributes)
(tramp-perl-directory-files-and-attributes)
(tramp-perl-encode-with-module, tramp-perl-decode-with-module)
(tramp-perl-encode, tramp-perl-decode, tramp-perl-pack)
(tramp-perl-unpack, tramp-hexdump-encode, tramp-awk-encode)
(tramp-hexdump-awk-encode, tramp-od-encode, tramp-od-awk-encode)
(tramp-awk-decode): Use format specifiers supported by
`tramp-expand-script'.  Adapt docstring.
(tramp-vc-registered-read-file-names): Adapt docstring.
(tramp-sh-handle-file-local-copy): Let-bind local `default-directory'.
(tramp-expand-script): New defun.
(tramp-maybe-send-script, tramp-find-inline-encoding): Use it.
(tramp-local-coding-commands): Simplify.