[Cleanup] Rename BaseLevel to AbstractPhase, corresponding changes

...in/java/com/example/demo/controller/PhasesController.java

src/main/java/com/example/demo/domain/AbstractPhase.java

src/main/java/com/example/demo/domain/InfoPhase.java

...main/java/com/example/demo/domain/QuestionnaireLevel.java

src/main/java/com/example/demo/domain/Task.java

src/main/java/com/example/demo/domain/TrainingPhase.java

src/main/java/com/example/demo/dto/AbstractPhaseDto.java

src/main/java/com/example/demo/dto/InfoPhaseDto.java

...main/java/com/example/demo/dto/QuestionnaireLevelDto.java

src/main/java/com/example/demo/dto/TaskDto.java

src/main/java/com/example/demo/dto/TrainingPhaseDto.java

...ain/java/com/example/demo/facade/TrainingPhaseFacade.java

src/main/java/com/example/demo/mapper/BeanMapper.java

.../com/example/demo/repository/AbstractPhaseRepository.java

src/main/java/com/example/demo/service/InfoPhaseService.java

...java/com/example/demo/service/LevelOperationsService.java

src/main/java/com/example/demo/service/PhaseService.java

.../java/com/example/demo/service/QuestionChoiceService.java

...a/com/example/demo/service/QuestionnaireLevelService.java

...n/java/com/example/demo/service/TrainingPhaseService.java