Bulk refund event tickets

[engram-design]

It might happen that you want to cancel an event and refund all tickets.

We would need to go through any purchased tickets for the event, look up their corresponding order (if one), and line item for the sold price (we can't rely on the current price of the ticket in the event config), and if the gateway supports it, mass refund.

We'll want to be careful when dealing with this, as we're handling refunds on a bulk-scale.

This needs to be:

• Opt-in, maybe a deleted event doesn't issue refunds
• A separate utility. What happens when you accidentally delete an event (it becomes soft-deleted) and you restore it. Refunds will have gone out.
• Probably have a "Issue refunds" button in the event that you should run before deleting the event.
• Ability to set a note to be used on all refund transactions
• Identify if the gateway can handle a refund or not
• Show a report at the end with how everything went