bug#73723: 31.0.50; Add copy/kill/mark commands to isearch

[Phil Sainty <psainty@orcon.net.nz>]

I find the following useful, and sometimes see others asking for
the same thing.  Shall we add these to Emacs?

  (defun isearch-copy-match ()
    "Copy the currently-matched text to the kill ring."
    (interactive)
    (kill-new (buffer-substring (min (point) isearch-other-end)
                                (max (point) isearch-other-end))))

  (defun isearch-kill-match ()
    "Kill the currently-matched text."
    (interactive)
    (kill-region (min (point) isearch-other-end)
                 (max (point) isearch-other-end)))

  (defun isearch-mark-match ()
    "Exit isearch, marking the last match."
    (interactive)
    (set-mark isearch-other-end)
    (isearch-exit)
    (activate-mark))

  (define-key isearch-mode-map (kbd "M-s M-w") #'isearch-copy-match)
  (define-key isearch-mode-map (kbd "M-s C-w") #'isearch-kill-match)
  (define-key isearch-mode-map (kbd "M-s C-SPC") #'isearch-mark-match)
  (define-key isearch-mode-map (kbd "M-s C-@") #'isearch-mark-match)