Allow video autoplay when creating new dashboard tab.

[GrahamDumpleton]

Is your feature request related to a problem? Please describe.

I want to be able to have an embedded YouTube video opened using dashboard:create-dashboard autoplay.

Google requires allow=autoplay attribute on the iframe as well as ?autoplay=1 in the URL.

Describe the solution you'd like

Where have:

```dashboard:create-dashboard
name: Example
url: https://www.example.com/
```

Allow some extra attributes which enables video autoplay.

Describe alternatives you've considered

No response

Additional information

No response