ElementInternals: update `getAccessibleRefs`

`commons.aria.getAccessibleRefs` is a function that creates a map of elements with ids to elements that use that id in an idref(s) attributes. So for example, if the DOM looks like this:

```html

```

The function would create a map that more or less looks like this:

```js
{
document: {
div: [button]
}
}
```

The function needs to be updated to be able to handle lookups for elements that are referenced by elementInternal idref properties. We also want to be add a new feature to support filtering the returned elements by a specific ARIA attribute / property (e.g. only returning a list of elements that reference using `aria-labelledby`.

Start at commons.aria.getAccessibleRefs and inspect how it builds references from ARIA idref(s) attributes. Update the lookup to include ElementInternals idref properties and support filtering by a specified ARIA attribute or property; done when both reference types and filtering are handled.

Written by the indexing model from the issue text.