Run `man' also on remote systems

Run `man' also on remote systems

This implements bug#66758

* doc/emacs/programs.texi (Man Page):
Describe Man-support-remote-systems.

* etc/NEWS: Mention user option 'Man-support-remote-systems'.
Fix typos.

* lisp/dired.el (Man-support-remote-systems): Declare.
(dired-do-man): Use it.  Use also `file-local-name'.

* lisp/man.el (Man-support-remote-systems): New defcustom.
(Man-xref-normal-file): Handle remote files.
(Man-default-directory, Man-shell-file-name)
(Man-header-file-path): New defuns.
(Man-init-defvars): Use octal numbers.
(Man-support-local-filenames): Handle remote files.
(Man-completion-table): Use `Man-default-directory' and `process-file'.
(man): Adapt docstring.
(Man-start-calling): Use `Man-default-directory'.
(Man-getpage-in-background): Use `Man-default-directory',
`Man-shell-file-name', `start-file-process' and `process-file'.  Adapt
buffer name.
(Man-update-manpage): Use `Man-shell-file-name' and `process-file'.
(Man-view-header-file): Use `Man-header-file-path'.