closeEditing method
Closes the editing if any.
Implementation
void closeEditing() {
  final bool hadFocus = edit.value?.field.focus.hasFocus == true;
  edit.value?.field.focus.removeListener(_stopTypingOnUnfocus);
  edit.value?.onClose();
  edit.value = null;
  if (!PlatformUtils.isMobile && hadFocus) {
    send.field.focus.requestFocus();
  }
}