refactor: complete hexagonal architecture - ports and adapters pattern

- Remove old package directories (controller/, dto/, service/, repository/, connector/, config/, security/, model/)
- Update test package declarations to match new hexagonal structure
- Move test files to corresponding new package directories
- Final cleanup to complete hexagonal architecture migration

Package structure:
  domain/model/        <- domain entities
  domain/port/input/   <- inbound use-case interfaces
  domain/port/output/  <- outbound port interfaces
  application/service/ <- application services
  adapter/input/rest/  <- REST controllers and DTOs
  adapter/output/persistence/ <- JPA repositories
  adapter/output/connector/   <- database connectors
  infrastructure/config/      <- Spring configuration
  infrastructure/security/    <- JWT security

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: MaximumTrainer

backend/src/main/kotlin/com/opendatamask/adapter/output/connector/ConnectorFactory.kt

@@ -1,7 +1,7 @@
 package com.opendatamask.adapter.output.connector
 
 import com.opendatamask.domain.model.ConnectionType
-import com.opendatamask.service.FileStorageService
+import com.opendatamask.application.service.FileStorageService
 import org.springframework.stereotype.Component
 
 @Component