Optimizations on Tramp symlink handling

Optimizations on Tramp symlink handling

* lisp/net/tramp-sh.el (cl-seq): Require.
(tramp-perl-file-truename): Print also whether the file is a symlink.
(tramp-bundle-read-file-names): Rename from
`tramp-vc-registered-read-file-names'.  Print also the
`file-directory-p: value.
(tramp-sh-handle-make-symbolic-link): Combine two commands.  Use
`tramp-skeleton-make-symbolic-link'.
(tramp-sh-handle-file-truename): Read also "file-symlink-marker"
property.
(tramp-sh-handle-file-directory-p): Simplify if-let clause.
(tramp-sh-handle-file-name-all-completions): Simplify command.
(tramp-bundle-read-file-names): New defun.
(tramp-sh-handle-vc-registered, tramp-get-remote-path): Use it.
(tramp-open-shell): Flush "scripts" connection property.
(tramp-open-connection-setup-interactive-shell): Combine two commands.

* lisp/net/tramp-smb.el (tramp-smb-handle-make-symbolic-link):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-make-symbolic-link):
Use `tramp-skeleton-make-symbolic-link'.

* lisp/net/tramp.el (tramp-skeleton-make-symbolic-link): Rename from
`tramp-skeleton-handle-make-symbolic-link'.
(tramp-handle-file-symlink-p): Check file property
"file-symlink-marker".