…orms

Before this commit, the payment providers (e.g., Stripe, Adyen...)
available for payment were displayed on the payment forms. The customer
had to select one to process their payment. After that, the customer had
to select their preferred payment method (e.g., Credit Card,
Bancontact...) from a list of payment methods supported by the selected
provider over which the website administrator had close to no control.
This was making the payment forms confusing because the payment methods
were displayed sometimes more than once, if at all, in a non-controlled
order, and behind the selection of a payment provider that customers
should not have to deal with.

As the payment method was selected in an iframe or directly on the
provider's website, the information on the selection payment method was
not available in Odoo. This posed many problems, among which were the
impossibility of assessing whether a specific feature (e.g.,
tokenization, refunds, manual capture...) was available, not being able
to easily identify payment tokens through the payment method logo,
listing available payment methods on the website, sorting and
fine-grained configuration of the available payment method, subpar
payment method-specific display on the payment form (e.g., PayPal that
requires displaying a "Pay with PayPal" button), etc.

In this commit, the payment providers are thus replaced by the payment
methods on the payment forms. All contextually available (depending on
the country, currency, requested feature...) payment methods are
displayed one after the other on a single-level list and in the order
configured by the website administrator. Each payment method is
"powered by" (i.e., linked) to a single payment provider: the first one,
by model order, to support it. This allows, for example, offering the
PayPal payment method through Mollie, which charges low processing fees,
while also offering Klarna through Stripe, which supports more payment
methods but charges higher processing fees.

While doing so, the two different payment forms, "Checkout" and
"Manage", are also merged together in a new, configurable case-by-case,
payment form that is entirely redesigned to offer a better user
experience.

After payment, the information on the selected payment method is saved
on the transaction and eventual payment record and updated with the
information received from the provider.

task-2882677

closes #120446

Related: odoo/upgrade#5103
Related: odoo/documentation#5717
Related: odoo/enterprise#40666
Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>
Co-authored-by: Anita (anko) <anko@odoo.com>
Co-authored-by: Brieuc-brd <brd@odoo.com>
Co-authored-by: Valeriya (vchu) <vchu@odoo.com>

task-2882677

closes #5717

Related: odoo/upgrade#5103
Related: odoo/odoo#120446
Related: odoo/enterprise#40666
Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>