Feat#3 session badges

[LeonardoVieira1630]

Pull request made to complete this task: https://github.com/orgs/blockful-io/projects/16/views/1?pane=issue&itemId=83822933&issue=blockful-io%7Cbackend-zucity%7C3

The context is that we will now have "session" in the contract. Each villager can create a session. Each session automatically creates two new badges that only the session host can attest.
To achieve this, the following items were added:

1. A map to store sessions (_session)
2. A function to create a session (createSession())
3. A function to check if the attestation is a session_attestation (isHostOnlyAttestation)
4. A function to check if the attester is the host (isAttesterHost)
5. A utility function slice() to get the first part of the attestation title
6. Tests to validate the functionality of the new code.

[lgahdl]

Seems good!

[RafaDSan]

Hey, Leo! If it makes sense I would like to make two suggestions:

1. Emit an event when a session is created
   Reason: Make it easy to access on the blockchain side in case it is necessary; Easy to track

Resolver.sol

 event SessionCreated(
        bytes32 indexed sessionId,
        address indexed host,
        string title,
        uint256 startTime,
        uint256 endTime
    );
    
    //function createSession()
     emit SessionCreated(
            sessionId,
            msg.sender,
            sessionTitle,
            session.startTime,
            session.endTime
        );

2. Add function to end or cancel a session and session status (like: Active, Ended, Cancelled)
   Reason: Keep track of the session status; Make the user finish the session despite the time

Like:

  enum SessionStatus { Active, Ended, Cancelled }
    
    struct Session {
        address host;
        string title;
        uint256 startTime;
        uint256 endTime;
        SessionStatus status; 
    }

[RafaDSan]

These are optional suggestions, so feel free to disagree in case they do not make sense to you!
Also, good job with the testing coverage and code organization

[LeonardoVieira1630]

Hi Rascar, ty for the review brother.

1- Great catch related to the event bro! Makes our lives easier. I will implement it.
2- I think that the status adds a complexity that is not ideal. Look, to modify a status in the struct, it would be necessary to call a function and pay for it. The best approach is just keep looking for the endTIme. If someone wants to know if a session is still valid, just need to look if currentTime<endTime.