Implement GitHub Authentication necessary changes (Server has the OAuth flow using passport.js)

[foyzulkarim]

Description:

This pull request is the client side change for the server implementation from CommitStreams Server:
Implement GitHub Authentication using Passport.js

The changes are primarily focused on managing authentication states, handling login/logout flow, and setting up the necessary routes.

Changes:

1. AuthContext.js: This file has been updated to handle the authentication states and user profile information. It uses the React Context API to provide a global state for authentication, which can be accessed across the application.

2. Login/Logout Flow: The login and logout flow has been implemented. On successful GitHub authentication, the user will be redirected to the dashboard/home page. On logout, the user will be redirected back to the login page.

3. Routes: Routes have been set up for the login and logout process. The /auth/github route initiates the GitHub authentication process, while the /auth/github/callback route handles the callback from GitHub after user authentication.