How to insert() embed programmatically?

For example, imagine typing the `source` URL in a text input, then feeding it to the `insert()` method:

```js
editor.blocks.insert('embed', {source: url}, {}, index, true)
```

Of course, that won't work because the `service` and `embed` URL have not been set.

How can you insert an embed block based just on the `source` URL, without parsing the `service` and `embed` URL yourself?