Toggle: plugin behaviour fixes

1. Fix first click on elements that toggle themselves.
2. Fix setAriaControls to set unique IDs on elements that don't have an ID defined.
3. Group toggle elements no longer default to `"type": "on"` (fixes #3711).  This allows the currently open section of an accordion to be closed.

**Breaking change**

Group toggle elements that you do not want to allow closed must specify their type as on:

```html
data-toggle='{"group": ".grouped", "type": "on"}'
```



/cc @masterbee