Refactoring and Error Handling Enhancements

[foyzulkarim]

Refactoring and Error Handling Enhancements

This pull request includes several significant updates to improve the code structure and error handling in our application. Here's a summary of the changes:

Refactor Auth and GitHub Strategy

We've refactored our authentication logic to improve its readability and maintainability. The GitHub OAuth strategy has been updated to enhance the security and efficiency of our GitHub authentication process.

Refactor User API

The API endpoints related to user operations have been refactored. These changes aim to improve the structure of our endpoints and the efficiency of the underlying logic. This refactoring will make our user API more robust and easier to maintain.

Introduced ValidationError

We've introduced a new error type, ValidationError. This error type will be used to handle validation failures throughout our application. By using a dedicated error type for validation failures, we can provide more specific error messages and make our error handling code more consistent.

Added mocks

We've added a __mocks__ directory to our project. This directory contains mock objects and functions that we can use in our unit tests. These mocks will help us write tests that are more focused and reliable, by allowing us to simulate the behavior of our application's dependencies.