Added support for S3 storage classes (#28319)

* Added support for S3 storage classes

* Added missing translations for S3 storage class

* Changed default storage class values to preserve original behaviour

* Changed storage class description and example

* Fix translations ordering

* Change configuration defaults to empty strings

* Remove redundant empty string check

* Validate storage class variable against constants from S3 API docs

* Validate export storage class against constants

* Use slices for config validation

* Applied patch for translation ordering

server/tests/test-config.json

@@ -136,7 +136,8 @@
         "AmazonS3SSL": true,
         "AmazonS3SignV2": false,
         "AmazonS3SSE": false,
-        "AmazonS3Trace": false
+        "AmazonS3Trace": false,
+        "AmazonS3StorageClass": ""
     },
     "EmailSettings": {
         "EnableSignUpWithEmail": true,