User cannot authenticate with Peak Response if they do not have a Vehicle assignment

[francisli]

Currently, the Vehicle assignment is used to identify the Agency that the User belongs to for creating the User's account with the right Organization in Routed.

Consider passing the Agency subdomain identifier to Routed so that it can be included as a scope for authenticating the User with Peak Response. When authenticating using the subsequently created access token, the scope can then be used to look up the associated Agency.