[Clean-up] Planned removal of the `max_size` argument

- Replace deprecated `"feature_extractor_type": "DetrFeatureExtractor"` with `"image_processor_type": "DetrImageProcessor"`
- Remove deprecated `max_size` and replace `size` with a `Dict`

preprocessor_config.json

@@ -1,7 +1,7 @@
 {
   "do_normalize": true,
   "do_resize": true,
-  "feature_extractor_type": "DetrFeatureExtractor",
+  "image_processor_type": "DetrImageProcessor",
   "format": "coco_detection",
   "image_mean": [
     0.485,
@@ -13,6 +13,8 @@
     0.224,
     0.225
   ],
-  "max_size": 1333,
-  "size": 800
-}
+  "size": {
+    "longest_edge": 1333,
+    "shortest_edge": 800
+  }
+}