Before this commit, it was not possible to refund a payment from Odoo.
Users had to go through the payment acquirer's backend and update the
payment accordingly in Odoo.
With this commit, refunds are made available in Odoo directly from the
payment form, for acquirers that support them. Acquirer can either only
support full refunds or also support partial refunds.
As of now, the only acquirer allowing refunds is Adyen, with partial
refund support.
task-2527891
closesodoo/odoo#70881
Related: odoo/upgrade#2689
Related: odoo/enterprise#19829
Signed-off-by: Antoine Vandevenne (anv) <AntoineVDV@users.noreply.github.com>