New user options 'copy-region-blink-delay' and 'delete-pair-blink-delay'

New user options 'copy-region-blink-delay' and 'delete-pair-blink-delay'

* lisp/emacs-lisp/lisp.el (delete-pair-blink-delay): New defcustom.
(delete-pair): Use it.  (Bug#4136)

* lisp/simple.el (copy-region-blink-delay): New defcustom.
(indicate-copied-region): Use it.  (Bug#42865)
Thanks to Sean Whitton <spwhitton@spwhitton.name>.
(indicate-copied-region): Use 'query-replace-descr' not to show
newlines literally.  Use "Copied text" instead of misleading
"Saved text" (bug#42865).