Add rules for datasets and transforms imports (#61)

## Context

* There is a linter rule that recommends changing `import
torchvision.models as models` to `from torchvision import models`
* The same behavior is expected for `torchvision.datasets` and
`torchvision.transforms`

## Changes

* Extend the `models` rule to also address the first instance of the
`datasets` and `transforms` imports
* Rename the models import checker and related fixtures to be more
generic since more imports are checked now

## Testing

* Updated existing unit test and fixture
* No lint errors for modified files

Author: XIIFulminata

tests/fixtures/vision/checker/models_import.txt

@@ -4,3 +4,5 @@
 import torchvision.models
 from torchvision.models import *
 import torchvision.models as models, torch
+import torchvision.datasets as datasets
+import torchvision.transforms as transforms

tests/fixtures/vision/checker/models_import.py renamed to tests/fixtures/vision/checker/singleton_import.py

@@ -0,0 +1,4 @@
+1:1 TOR203 Consider replacing 'import torchvision.models as models' with 'from torchvision import models'.
+6:1 TOR203 Consider replacing 'import torchvision.models as models' with 'from torchvision import models'.
+7:1 TOR203 Consider replacing 'import torchvision.datasets as datasets' with 'from torchvision import datasets'.
+8:1 TOR203 Consider replacing 'import torchvision.transforms as transforms' with 'from torchvision import transforms'.

tests/fixtures/vision/checker/singleton_import.txt

@@ -0,0 +1,9 @@
+import torchvision.models as models
+import torchvision.models as cnn
+import torchvision.datasets as datasets
+import torchvision.datasets as datasets_alt
+import torchvision.transforms as transforms
+import torchvision.transforms as transforms_alt
+
+# don't touch if more than one name imported
+import torchvision.models as models, torch

tests/fixtures/vision/codemod/models_import.py

@@ -0,0 +1,9 @@
+from torchvision import models
+import torchvision.models as cnn
+from torchvision import datasets
+import torchvision.datasets as datasets_alt
+from torchvision import transforms
+import torchvision.transforms as transforms_alt
+
+# don't touch if more than one name imported
+import torchvision.models as models, torch

tests/fixtures/vision/codemod/models_import.py.out

@@ -16,7 +16,7 @@
 from .visitors.vision import (
     TorchVisionDeprecatedPretrainedVisitor,
     TorchVisionDeprecatedToTensorVisitor,
-    TorchVisionModelsImportVisitor,
+    TorchVisionSingletonImportVisitor,
 )
 from .visitors.security import TorchUnsafeLoadVisitor
 
@@ -33,7 +33,7 @@
     TorchSynchronizedDataLoaderVisitor,
     TorchVisionDeprecatedPretrainedVisitor,
     TorchVisionDeprecatedToTensorVisitor,
-    TorchVisionModelsImportVisitor,
+    TorchVisionSingletonImportVisitor,
     TorchUnsafeLoadVisitor,
     TorchReentrantCheckpointVisitor,
     TorchNonPublicAliasVisitor,

tests/fixtures/vision/codemod/singleton_import.py

@@ -1,3 +1,3 @@
 from .pretrained import TorchVisionDeprecatedPretrainedVisitor  # noqa: F401
 from .to_tensor import TorchVisionDeprecatedToTensorVisitor  # noqa: F401
-from .models_import import TorchVisionModelsImportVisitor  # noqa: F401
+from .singleton_import import TorchVisionSingletonImportVisitor  # noqa: F401