feat: make repository interface functional

Author: andrea-acampora

src/main/kotlin/usecase/repository/AuthenticationRepository.kt

@@ -14,7 +14,7 @@ import io.vertx.core.Future
 /**
  * interface for user authentication repository.
  */
-interface AuthenticationRepository {
+fun interface AuthenticationRepository {
 
     /**
      * Authenticate a user.

src/main/kotlin/usecase/repository/SurgicalProcessRepository.kt

@@ -15,7 +15,7 @@ import io.vertx.core.Future
 /**
  * Repository to manage and obtain data for Surgical Processes.
  */
-interface SurgicalProcessRepository {
+fun interface SurgicalProcessRepository {
 
     /**
      * Get a [SurgicalProcess] by the [preOperatingRoomId] and the [operatingRoomId].