Resume billing for a session whose billing was suspended by a failed validation rule, completing it either with the
session amounts as they are or as a free session. The action runs as the token owner, who is recorded on the session
edit log and on the action audit record.

Requires the Sessions.resume-billing permission - a token whose admin does not hold it is rejected with 403, and so
is a request for a session that belongs to another operator. An unknown session ID is rejected with 404.

Preconditions, with the response code each failure produces:

• billingStatus is suspended - otherwise 409
• The session is no longer underway at the charge point - otherwise 409. Not every pending or active session
  is rejected: a pending session that has not been sent to the charge point yet, and an active session that
  has stopped and is waiting for the cable to be unlocked, are not underway and are accepted.
• Billing for the session is not owned by the upstream roaming partner - otherwise 409
• For free_session: the session has no order yet, unless the platform settings allow marking a session that
  already has an order as free - otherwise 409
• No recalculation is running for the session and the session is not locked for billing processing - otherwise 423
• type holds one of the documented values and reason is at most 1000 characters - otherwise 422

The validation rules are not re-run, so both type values end with billingStatus set to completed: bill_as_is
keeps the session amounts and charging periods as they are, and free_session zeroes the amount charged to the
driver first. This action cannot leave the session suspended.

When billing cannot be completed after every precondition has passed, the session is left untouched and the action
answers 409.