fix(attachment): Restrict access to security user.

Signed-off-by: rudra-superrr <prabhuchopra@gmail.com>

Author: rudra-superrr

rest/resource-server/src/main/java/org/eclipse/sw360/rest/resourceserver/attachment/AttachmentController.java

@@ -160,6 +160,7 @@ public ResponseEntity<CollectionModel<EntityModel<Attachment>>> createAttachment
         }
         final User sw360User = restControllerHelper.getSw360UserFromAuthentication();
         List<EntityModel<Attachment>> attachments = new ArrayList<>();
+        restControllerHelper.throwIfSecurityUser(sw360User);
         for (MultipartFile file: files) {
             Attachment attachment = attachmentService.addAttachment(file, sw360User);
             attachments.add(EntityModel.of(attachment));