Save *.npy features on detect.py --visualize (#5701)

* Add feature map to save npy files

Add feature map to save npy files,export npy files with 32 feature maps per layer.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update plots.py

* Update plots.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update plots.py

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

tutorial.ipynb

@@ -1104,4 +1104,4 @@
       "outputs": []
     }
   ]
-}
+}