Improve logout functionality and guards behavior

[hootanht]

Related to #14

Implements an alternative solution for logging out without closing browser tabs, and enhances authentication guards.

• Authentication Service: Modifies the loginOut method to clear local storage and navigate to the login page instead of reloading the window. This change ensures a smoother logout process without closing the browser tab.
• Authentication Guard: Updates the canActivate method to check for the existence of an 'auth_token' in local storage and redirects to the login page if not found. This strengthens the security by ensuring that navigation is only allowed for authenticated users.
• UnAuthentication Guard: Adjusts the canActivate method to redirect authenticated users to the home page, preventing access to authentication-related pages for users who are already logged in.
• Logout Component: Changes the logout logic to navigate to the login page after logging out, ensuring users are redirected appropriately.
• Unit Tests: Adds and updates unit tests for the AuthenticationService and guards to cover the new logout behavior and guard functionality, ensuring the changes work as expected.

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