Remove unused imports and fix syntax formatting in DropzoneController files.

# Conflicts:
#	src/Dropzone/assets/src/controller.ts

Author: Carlos Hernández

src/Dropzone/assets/src/controller.ts

@@ -22,8 +22,7 @@ export default class extends Controller {
         'previewClearButton',
         'previewFilename',
         'previewImage',
-        'previewContainer'
-    ,
+        'previewContainer',
     ];
 
     files: Map<string, File> = new Map<string, File>();