1. Datasets.java: In "delete()" method, call also fileManager.markAllFilesOfEntityIdAsDeleted.
2. DatasetManager.java: Added method "deleteOldFilesAndAddNew()" which is called by "createOrUpdate()", to mark as deleted files that are not used any more and save the new ones.
3. DatabaseRepository.java & DatabaseRepositoryImpl.java: Include in DAOs FileUploadDAO.
4. ModelBuilder.java & ViewStyle.java: Incluse "upload" field type.
5. field-data.ts:
a. In "getOrdinal()" method return Integer instead of int.
b. In "getValidations()" method added null check.
c. In methods "fromJsonObject()" and "toMap()" added special if clauses for "upload" field type.
6. application.properties:
a. Added property "file.storage", to set the folder where the files will be permanently saved.
b. Changed default spring.servlet.multipart.max-file-size and pring.servlet.multipart.max-request-size to 10 MB.
7. UserInvitationController.java: Deleted a print in System.out.
8. New files for upload field type: FileUploadDao.java, FileUploadDaoImpl.java, FileUpload.java, PostgreSQLEnumType.java (necessary for the enum EntityType), FileController.java, FileManager.java, UploadData.java.