feat(storage): provide optional chunk size field for GetObject

internal/plugin/loopback/storage_test.go

@@ -629,6 +629,18 @@ func TestLoopbackGetObject(t *testing.T) {
 			},
 			expectedErr: codes.PermissionDenied,
 		},
+		{
+			name: "with chunk size",
+			request: &plgpb.GetObjectRequest{
+				Key: "mock_object",
+				Bucket: &storagebuckets.StorageBucket{
+					BucketName: "aws_s3_mock",
+					Secrets:    secrets,
+				},
+				ChunkSize: 3,
+			},
+			expectedObj: mockStorageMapData["aws_s3_mock"]["mock_object"],
+		},
 		{
 			name: "object retrieved",
 			request: &plgpb.GetObjectRequest{