Refactor State-Based Logic in authenticate function to Request-Type-Based Logic

[CFIALeronB]

Problem: The previous implementation of the authenticate function heavily relied on a state-based logic. This approach transitioned between multiple states such as INITIAL_STATE, AWAITING_EMAIL, EMAIL_SENT, and USER_AUTHENTICATED.

Solution: The function has now been refactored to handle different types of requests based on the presence and type of token in the request. Specifically:

1. For requests with both a valid client JWT and an email:

   • The provided email is validated.
   • A verification token is generated and an email is sent to the provided address.

2. For requests with a valid client JWT but without an email:

   • Users are redirected to the Louis login frontend.

3. For requests where client JWT decoding fails:

   • The function attempts to decode using the verification token method, to validate users trying to confirm their emails.

In addition to the main changes, the following were done:

• Removal of state transition functions previously employed.
• Introduction of test cases that focus on JWT validation.

This change should make the code more streamlined, easier to maintain, and reduce potential points of failure.