feat(ui): include compositor info with multigrid

Provide compositor information, like composition index and absolute
position.

src/nvim/ui.c

@@ -545,6 +545,9 @@ void ui_flush(void)
   if (pending_cursor_update) {
     ui_call_grid_cursor_goto(cursor_grid_handle, cursor_row, cursor_col);
     pending_cursor_update = false;
+    // The cursor move might change the composition order, so flush again to update the windows that
+    // changed
+    win_ui_flush(false);
   }
   if (pending_mode_info_update) {
     Arena arena = ARENA_EMPTY;