Erase a user's data from one provider

Erases everything the user holds from one provider without touching any connection: the route for device providers (apple_health, health_connect), which have no connection, and for a provider already disconnected. A background job deletes every record, raw file and sync record of this user and provider; the user and their other providers stay. The answer is 202 with the job_id to poll at GET /v1/deletions/{job_id}; asking again while it runs returns the same job. Until it is done, uploads of that provider for the user are refused (409). A provider the user is still connected to is a 409: use DELETE /v1/users/{id}/connections/{provider}?delete_data=true. A provider unknown to this build is a 404.