[WIP] Move driver details into the local database

[AlexGilleran]

Currently driver details live in Auth0, which means that we can only store information about them in crude ways, and it also meant that they're out of reach of the reporting that gets done from the database.

We want to change this so that information about drivers (e.g. do they have an SUV?) is stored in the database, but authentication (e.g. their password or however they log in) continues to be done in Auth0.

What we need to do

UI

• Screen to CRUD drivers (clone clients?)
• API for driver CRUD

Database

• Create a table to hold existing driver details, including auth0 id
• Add "inactive" flag to the table
• Change existing references to the driver from driver email address to a foreign key to the driver table

Migration

• Run a script to copy existing drivers to the database
• Migrate from existing email address references to an FK to the driver table

Email

• Change to getting drivers from the database
• Only send to inactive drivers