feat(checkout): build payment section

[mapra99]

Closes #36

This PR implements the payments section for checkout. The flow basically goes as follows:

• After authenticating and submitting the location, the user will go to the payment page
• During the page load, the frontend server will hit a backend endpoint to create a payment record on the DB and also hit the Stripe API to create a payment_intent. The frontend server will receive a client_secret that identifies the payment_intent.
• The frontend in the browser will use the stripe.js library to use the client_secret and render the Stripe payment form.
• The user submits the form, and Stripe will process the payment. When the payment is successful, Strip will notify a webhook in the backend to update the payment status on the DB. Also, the Stripe components on the frontend will redirect the user to a thank you page. If the payment fails the flow is analogous.

https://www.loom.com/share/fc0bc160ec444e41b0199784d9ec7e34

[ImMPrada]

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