toggleSelected(editor) {
    if (this.#selectedEditors.has(editor)) {
      this.#selectedEditors.delete(editor);
      editor.unselect();
      this.#dispatchUpdateStates({
        hasSelectedEditor: this.hasSelection,
      });
      return;
    }
    this.#selectedEditors.add(editor);
    editor.select();
    this.#dispatchUpdateUI(editor.propertiesToUpdate);
    this.#dispatchUpdateStates({
      hasSelectedEditor: true,
    });
  }
Add or remove an editor the current selection.
@param {AnnotationEditor} editor