check payment methods resource against api reference

[VictorAvelar]

Description

Ensures that the payment methods resource delivers API parity.

Motivation and context

Ensures the library has full API parity.

How has this been tested?

Please describe in detail how you tested your changes.

Include details of your testing environment, and the tests you ran to see how your change affects other areas of the code, etc.

• [x] Unit tests added / updated
• [x] The tests run on docker (using make test)
• [ ] The required test data has been added / updated

If you are running the tests locally, please specify:

• OS: macos
• Go version 1.22

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] This change requires a documentation update

Checklist

Go over all the following points, and put an x in all the boxes that apply.

Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our continuous integration server to make sure your tests and code style pass.

• [x] I have read the CONTRIBUTING document.
• [x] My pull request addresses exactly one patch/feature.
• [x] I have created a branch for this patch/feature.
• [x] Each individual commit in the pull request is meaningful.
• [x] If my change requires a change to the documentation, I have updated it accordingly.