Download ref/scripts on runtime to avoid sphinx gallery issues with these files

Author: vfdev-5

.jenkins/validate_tutorials_built.py

@@ -51,11 +51,6 @@
     "intermediate_source/flask_rest_api_tutorial",
     "intermediate_source/text_to_speech_with_torchaudio",
     "intermediate_source/tensorboard_profiler_tutorial", # reenable after 2.0 release.
-    "intermediate_source/engine",  # helper file for torchvision_tutorial.py
-    "intermediate_source/utils",  # helper file for torchvision_tutorial.py
-    "intermediate_source/coco_utils",  # helper file for torchvision_tutorial.py
-    "intermediate_source/coco_eval",  # helper file for torchvision_tutorial.py
-    "intermediate_source/transforms",  # helper file for torchvision_tutorial.py
 ]
 
 def tutorial_source_dirs() -> List[Path]:

Makefile

@@ -114,11 +114,6 @@ download:
 	# and detection reference scripts: engine.py, utils.py ...
 	wget https://www.cis.upenn.edu/~jshi/ped_html/PennFudanPed.zip -P $(DATADIR)
 	unzip -o $(DATADIR)/PennFudanPed.zip -d intermediate_source/data/
-	wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/engine.py -P intermediate_source
-	wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/utils.py -P intermediate_source
-	wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/coco_utils.py -P intermediate_source
-	wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/coco_eval.py -P intermediate_source
-	wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/transforms.py -P intermediate_source
 
 docs:
 	make download

intermediate_source/torchvision_tutorial.py

@@ -312,8 +312,15 @@ def get_model_instance_segmentation(num_classes):
 # In ``references/detection/``, we have a number of helper functions to
 # simplify training and evaluating detection models. Here, we will use
 # ``references/detection/engine.py`` and ``references/detection/utils.py``.
-# Just copy everything under ``references/detection`` to your folder and use them here.
-#
+# Just download everything under ``references/detection`` to your folder and use them here.
+# On Linux if you have ``wget``, you can download them using below commands:
+
+os.system("wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/engine.py")
+os.system("wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/utils.py")
+os.system("wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/coco_utils.py")
+os.system("wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/coco_eval.py")
+os.system("wget https://raw.githubusercontent.com/pytorch/vision/main/references/detection/transforms.py")
+
 # Since v0.15.0 torchvision provides `new Transforms API <https://pytorch.org/vision/stable/transforms.html>`_
 # to easily write data augmentation pipelines for Object Detection and Segmentation tasks.
 #