fix: use proper expiry time in getorder endpoint

[pavelbrm]

Summary

This PR fixes code that could update an order associated with Stripe purchases while getting the order. This could happen in a situation where:

• either an existing session has expired, and a new had been created;
• or when the existing or new session has been paid, which would then result in marking the order as paid, and setting it's expiry time as a consequence.

That last path is important because it used to extend an order by the hardcoded one month. This is wrong for a few reasons, mainly because:

• it can be set precisely using the end of a subscription from Stripe;
• it prevented us from sully supporting annual products in Stripe.

This PR also fixes a bug where a new session could be ignored to be checked for payment status.

This PR also refactors interactions with Stripe. The Stripe client code has been wrapped to enable testing. Some places interacting with Stripe have been updated and unified (such as session creation).

Additionally, this set of changes includes vast test coverage for the changed code (which was not covered before), as well as coverage for places which have not been possible to test before as well.

Type of Change

• Product feature
• Bug fix
• Performance improvement
• Refactor
• Other

Tested Environments

• Development
• Staging
• Production

Before Requesting Review

• Does your code build cleanly without any errors or warnings?
• Have you used auto closing keywords?
• Have you added tests for new functionality?
• Have validated query efficiency for new database queries?
• Have documented new functionality in README or in comments?
• Have you squashed all intermediate commits?
• Is there a clear title that explains what the PR does?
• Have you used intuitive function, variable and other naming?
• Have you requested security and/or privacy review if needed
• Have you performed a self review of this PR?

Manual Test Plan

[clD11]

🎉

[clD11]

😆

[clD11]

LGTM, approved with some questions and minor nit

[github-actions]

[puLL-Merge] - brave-intl/bat-go@2612

Description

This PR refactors the Stripe integration in the SKUs service, improving code organization, testability, and error handling. It moves Stripe-related logic into a separate package, introduces a new stripeClient interface, and updates the order processing flow.

Changes

Changes

1. services/skus/controllers.go:

   • Renamed GetOrder to handleGetOrder for consistency.
   • Updated error handling in handleGetOrder.

2. services/skus/model/model.go:

   • Removed Stripe-specific methods and structs from the Order model.
   • Added new methods like StripeSessID() and IsStripe() to Order.
   • Added StripeItemID() method to OrderItem.

3. services/skus/service.go:

   • Introduced stripeClient interface.
   • Refactored InitService to use the new Stripe client.
   • Updated CreateOrderFromRequest to remove Stripe-specific logic.
   • Implemented getTransformOrder and updateOrderStripeSession methods.
   • Added renewOrderStripe method for handling Stripe renewals.
   • Moved Stripe session creation logic to createStripeSession.

4. services/skus/xstripe/xstripe.go:

   • Created a new package for Stripe-related functionality.
   • Implemented Client struct wrapping Stripe's API client.
   • Added methods for interacting with Stripe API (Session, CreateSession, Subscription, FindCustomer).

5. services/skus/xstripe/mock.go:

   • Added a mock Stripe client for testing purposes.

6. Various test files:

   • Updated existing tests and added new ones to cover the refactored code.

Possible Issues

1. The refactoring may have introduced subtle changes in behavior that could affect existing integrations or workflows.
2. The new error handling in handleGetOrder might return different status codes in some cases, which could impact API consumers.

Security Hotspots

No significant security issues were introduced in this refactoring. However, care should be taken to ensure that sensitive information (like Stripe API keys) is properly handled and not exposed in logs or error messages.