[SELC-7792] feat: add ConflictException handler for error 409 from PDV in createOrUpdateByFiscalCode API

[duffizipierluigi]

List of Changes

• add ConflictException
• update ExceptionHandler
• update Cucumber test
• update unit test

Motivation and Context

To resolve error 409 in production when patching users on PDV when creating or updating user by fiscal code

How Has This Been Tested?

Locally, by unit test and cucumber tests

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[giulia-tremolada]

lgtm