Fix: Properly handle environment secrets in "convertProjectEnvironmentModelToEnvironmentRequest"

[lepichon]

Description

This PR updates the convertProjectEnvironmentModelToEnvironmentRequest function to correctly handle environment secrets when creating or updating a project environment. Previously, secrets were either ignored or incorrectly converted, causing issues when applying Terraform plans.

Changes

• Iterates over env.Secrets and creates EnvironmentSecretRequest objects.
• Properly sets the Operation field for create, update, and delete.
• Ensures that only changed secrets are marked for update, unchanged secrets are left intact.
• Deletes secrets present in the previous state but missing in the current plan.

Testing

• Verified creating a new environment with secrets creates correct EnvironmentSecretRequest objects.
• Verified updating secrets triggers the update operation only for changed secrets.
• Verified deleting secrets triggers the delete operation.
• Terraform state remains consistent after apply.