feat: create new exception types

[bruno-martins-mx]

Summary of Changes

Create new exception types for specific cases. Exceptions added:

• NotAuthenticatedException;
• SessionNotFoundException.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works