[CT-1548] Example script to demo click API usage

[MichelleArk]

Issue

Create an example script to demonstrate what calling the new click CLI programmatically will look like. The script will serve as a base to be iterated on as we work through API-ification so that it serves as a live spec of the API-ified effort!

Exit Criteria:

To start, the demo script should provide example usage of calling any the dbt deps command programmatically, including capabilities to pass in certain objects and state and configure resources as necessary. Once dbt run is available in the new click CLI, include its usage in the example script.