Fix error message when signing with duplicate tx_id (Issue #60)

[Azzurriii]

Enhance error handling and improve the detection of duplicate signing requests in the event processing system regarding the Issue #60 . Include adding a new error code for duplicate sessions and updating the logic to handle duplicate signing requests.

• pkg/event/types.go: Added a new case in the GetErrorCodeFromError function to return ErrorCodeSessionDuplicate when the error string contains "duplicate". This improves the granularity of error categorization.

• pkg/eventconsumer/event_consumer.go: Enhanced the consumeTxSigningEvent function to handle duplicate signing requests. If a duplicate session is detected, an error message is logged, and the signing session error is handled explicitly using the handleSigningSessionError method. This ensures better tracking and management of duplicate requests.

Testing

Sent duplicate signing requests with the same tx_id.
Verified that the mpcium logs the duplicate and the client receives the error event in onSignResult

[anhthii]

@Azzurriii Thanks for the PR

In the error reason, I noticed "Duplicate signing request detected" two times

[Azzurriii]

Hey @anhthii, in those two instances of 'Duplicate signing request detected', one is an error message and the other is part of the context. You can see that in the log of mpcium

[anhthii]

thanks @Azzurriii , LGTM.