Added password field

- Added download error modal
- Added password field show logic
- Redesigned UI

src/main/java/de/w665/sharepulse/rest/mappings/Download.java

@@ -75,10 +75,13 @@ public class Download extends ApiRestController {
     public ResponseEntity<Object> getDownloadInfo(@RequestParam String fileId) {
         FileUpload fileUpload = fileService.getFileUploadByFileId(fileId);
 
+        boolean downloadable = !fileUpload.isSingleDownload() || fileUpload.getDownloadCount() == 0;
+
         Map<String, Object> response = new HashMap<>();
         response.put("fileId", fileUpload.getFileId());
         response.put("passwordProtected", fileUpload.isPasswordProtected());
         response.put("singleDownload", fileUpload.isSingleDownload());
+        response.put("downloadable", downloadable);
 
         return new ResponseEntity<>(response, HttpStatus.OK);
     }