Allow customers to cancel orders

[AndreiMaz]

Allow customerce to cancel orders on the order details page (public store). This is not the same as return requests.

Settings:

• This feature should be configurable (order settings). Disabled by default.
• Also add a setting indicating whether an order should be cancelled in this case. Or a notification will be sent to a store owner (without changing a status order)

Logic:

• Let's decide when this option will be available. For example, unpaid orders only. Or undelivered orders only. What should we do with refunds in this case?
• Once cancelled, a store owner should receive an email notification that an order has been cancelled by a customer.