feat: dto, exceptions and better database calls

src/main/kotlin/configuration/SecurityConfiguration.kt

src/main/kotlin/player/PlayerInfoDTO.kt

src/main/kotlin/player/PlayerRepository.kt

src/main/kotlin/player/PlayerRoute.kt

src/main/kotlin/player/PlayerService.kt

src/main/kotlin/player/PlayerServiceImpl.kt

src/main/kotlin/player/dtos/PlayerCreationDTO.kt

src/main/kotlin/player/dtos/PlayerInfoDTO.kt

src/main/kotlin/player/dtos/PlayerUpdateDTO.kt

...main/kotlin/player/exceptions/AlreadyExistingException.kt