New Donation Flow - Payment Intent Donations Endpoints

[dimitur2204]

Which area(s) of Podkrepi.bg are affected? (leave empty if unsure)

Donations

Describe the feature you'd like to request

We need an enpoint towards stripe to create and update a payment intent.
We currently don't have such endpoints.
Check out:

• https://stripe.com/docs/payments/accept-a-payment?platform=web&ui=elements#web-create-intent
• https://stripe.com/docs/api/payment_intents

This paymentIntent is needed if we want to inline the payment flow as described in podkrepi-bg/frontend#1267.

Describe the solution you'd like

We should be able to based on {amount=2000 currency=bgn payment_method_types=card}(https://stripe.com/docs/api/payment_intents/create). Create an endpoint returning the paymentIntent so the frontend can use it to initialize the Stripe Elements

Describe alternatives you've considered