Outbound Phone Calling on Playground

I imagine next to the "start" conversation buttons, we can have a button with a phone icon that opens up a modal to ask if the user wants to send an outbound call to a specific phone number.

We will want the user to only call their own number (clarify the law around outbound phone in the modal).

Users can fill in their number in the configs on the left panel, or then & there in the modal itself (will be same field as datasource in the PlaygroundContext, etc)