fix: s3 proxy return default bucket acl when tags not implemented

We currently store bucket ACLs as tags in the backend S3 service.
Some backend services do not implment tags though. In this case,
we need to return the default bucket ACL for some continued
functionality.

There is still more work to return more correct errors for setting
ACLs when this is not implemented.

backend/s3proxy/s3.go

@@ -1132,6 +1132,9 @@ func (s *S3Proxy) GetBucketAcl(ctx context.Context, input *s3.GetBucketAclInput)
 			if strings.Contains(ae.ErrorCode(), "NoSuchTagSet") {
 				return []byte{}, nil
 			}
+			if strings.Contains(ae.ErrorCode(), "NotImplemented") {
+				return []byte{}, nil
+			}
 		}
 		return nil, handleError(err)
 	}