| playable | The Playable used by this operation. |
| sourcePlayable | The Playable to connect to. |
| sourceOutputIndex | The output port of the Playable. |
Add a new input port and connect the output port of a Playable to this new port.
If several inputs are needed, it is better to use SetInputCount and ConnectInput.
This method is a simple helper on top of PlayableGraph.Connect.
NOTE: This is a templated extension method that can be used on any type that inherits from IPlayable.