fix(ui): cmdline_block events for exmode #37751

Problem:  Exmode is missing cmdline_block events.
Solution: Emit cmdline_block_show/append when executing a cmdline during
          exmode. Emit cmdline_block_hide when leaving exmode.

src/nvim/ex_docmd.c

@@ -5925,6 +5925,9 @@ void do_exedit(exarg_T *eap, win_T *old_curwin)
                         || eap->cmdidx == CMD_view)) {
     exmode_active = false;
     ex_pressedreturn = false;
+    if (ui_has(kUICmdline)) {
+      ui_ext_cmdline_block_leave();
+    }
     if (*eap->arg == NUL) {
       // Special case:  ":global/pat/visual\NLvi-commands"
       if (global_busy) {

src/nvim/ex_getln.c

@@ -1006,6 +1006,9 @@ theend:
   char *p = ccline.cmdbuff;
 
   if (ui_has(kUICmdline)) {
+    if (exmode_active) {
+      ui_ext_cmdline_block_append(0, p);
+    }
     ui_ext_cmdline_hide(s->gotesc);
   }
   if (!cmd_silent) {