feat(messages): confirm kind for z=, :tselect, inputlist() #32521

Problem:  Messages preceding a `cmdline_show->prompt` event can not be
          distinguished as such when receiving the event. (But since
          `msg_show` handlers should be scheduled, one can already check
          whether a prompt is active when displaying the message.)

Solution: Rather than add a new kind again, use the `confirm` kind.
          Could be seen as slightly misleading where it is more of
          a choice rather than a confirmation, but that already applies
          to `confirm()` as well...

src/nvim/spellsuggest.c

@@ -516,7 +516,7 @@ void spell_suggest(int count)
   spell_find_suggest(line + curwin->w_cursor.col, badlen, &sug, limit,
                      true, need_cap, true);
 
-  msg_ext_set_kind("list_cmd");
+  msg_ext_set_kind("confirm");
   if (GA_EMPTY(&sug.su_ga)) {
     msg(_("Sorry, no suggestions"), 0);
   } else if (count > 0) {