fix: simplified mock oauth with mswjs

[eddiejaoude]

Fixes Issue

We are using mswjs for mocking github API requests, while writing a blog on it, I thought it might simplify our code if we used the same process for mocking authenticated users during testing (and for offline development or when there is no github oauth app)

Changes proposed

Check List (Check all the applicable boxes)

• My code follows the code style of this project.
• My change requires changes to the documentation.
• I have updated the documentation accordingly.
• All new and existing tests passed.
• This PR does not contain plagiarized content.
• The title of my pull request is a short description of the requested changes.

Screenshots

Note to reviewers