Plaid Retrieve auth data

The `/auth/get` endpoint returns the bank account and bank identification numbers (such as routing numbers, for US accounts) associated with an Item's checking and savings accounts, along with high-level account data and balances when available. Note: This request may take some time to complete if `auth` was not specified as an initial product when creating the Item. This is because Plaid must communicate directly with the institution to retrieve the data. Versioning note: In API version 20...