Fire 'enabled' event when editor enabled state changes

[enzedonline]

This is needed to disable in-editor add-ons (such as blot-formatter2).

I'm currently implementing this via a mutation observer:

  private _qlDisabledObserver = new MutationObserver(mutations => {
    mutations.forEach(mutation => {
      if (mutation.type === 'attributes' && mutation.attributeName === 'class') {
        this.enabled = !this.quill.container.classList.contains('ql-disabled');
      }
    });
  });

I'd like to see a more robust method of detecting enabled state changes to the editor, an event that fires that includes the new state.