Improve temporary file handling in browse-url

Improve temporary file handling in browse-url

* lisp/net/browse-url.el (browse-url-delete-temp-file): Don't add
to kill-buffer-hook on top level.
(browse-url--temp-file-setup): New macro to set 'kill-buffer-hook'
buffer-locally to above function when creating a temporary file.  Use
stricter permissions to protect user privacy on multi-user systems.
(browse-url-of-file, browse-url-of-buffer): Use above new macro.

(browse-url-delete-temp-file): Simplify calling convention by removing
unused argument.

(cherry picked from commit 279a7d950ffff1b4f4a420848502a018b3998ee1)