Headless - allow 3D Secure check before placing the order

[jsims281]

Is your feature request related to a problem? Please describe.
As the order gets created before 3D secure is done, if the user fails the check then they are left in a state where they have a "dead" order on in Magento, and a new, empty quote. They must now start again with an empty cart if they want to place an order. The merchant is also left with an order that will not be fulfilled but may be affecting stock levels. Possibly related issue: #1986

Describe the solution you'd like
Provide an end point in the Adyen extension to allow us to present the user with 3D secure checks before placing the order.

Describe alternatives you've considered

• Modifying the Adyen M2 extension in-house, with patches or a private copy of the code
• Side-stepping the Adyen M2 extension entirely and doing the payment without it, then creating the order using a placeholder payment method