Add draft implementation

[dlackty]

Goal

Add a draft implementation based on Unified ID 2.0's API documentation.

Considerations

1. To simplify the code logic, faraday and middlewares are added as dependencies
2. For common uses cases, user of this project might use API client to consequent API calls, so net-http-persistent is added

Todos

• Properly handling and validation for API arguments

Discussions

• What's the right way to pass API arguments? Currently, positional arguments and hash as argument are both used in this project. Should we switch to keyword arguments?