Refactor mypy configs list into editor-friendly wrapper (#50826)

Summary:
Closes https://github.com/pytorch/pytorch/issues/50513 by resolving the first three checkboxes. If this PR is merged, I will also modify one or both of the following wiki pages to add instructions on how to use this `mypy` wrapper for VS Code editor integration:

- [Guide for adding type annotations to PyTorch](https://github.com/pytorch/pytorch/wiki/Guide-for-adding-type-annotations-to-PyTorch)
- [Lint as you type](https://github.com/pytorch/pytorch/wiki/Lint-as-you-type)

The test plan below is fairly manual, so let me know if I should add more automated tests to this PR.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/50826

Test Plan:
Unit tests for globbing function:
```
python test/test_testing.py TestMypyWrapper -v
```

Manual checks:

- Uninstall `mypy` and run `python test/test_type_hints.py` to verify that it still works when `mypy` is absent.
- Reinstall `mypy` and run `python test/test_type_hints.py` to verify that this didn't break the `TestTypeHints` suite.
- Run `python test/test_type_hints.py` again (should finish quickly) to verify that this didn't break `mypy` caching.
- Run `torch/testing/_internal/mypy_wrapper.py` on a few Python files in this repo to verify that it doesn't give any additional warnings when the `TestTypeHints` suite passes. Some examples (compare with the behavior of just running `mypy` on these files):
  ```sh
  torch/testing/_internal/mypy_wrapper.py README.md
  torch/testing/_internal/mypy_wrapper.py tools/fast_nvcc/fast_nvcc.py
  torch/testing/_internal/mypy_wrapper.py test/test_type_hints.py
  torch/testing/_internal/mypy_wrapper.py torch/random.py
  torch/testing/_internal/mypy_wrapper.py torch/testing/_internal/mypy_wrapper.py
  ```
- Remove type hints from `torch.testing._internal.mypy_wrapper` and verify that running `mypy_wrapper.py` on that file gives type errors.
- Remove the path to `mypy_wrapper.py` from the `files` setting in `mypy-strict.ini` and verify that running it again on itself no longer gives type errors.
- Add `test/test_type_hints.py` to the `files` setting in `mypy-strict.ini` and verify that running the `mypy` wrapper on it again now gives type errors.
- Remove type hints from `torch/random.py` and verify that running the `mypy` wrapper on it again now gives type errors.
- Add the suggested JSON from the docstring of `torch.testing._internal.mypy_wrapper.main` to your `.vscode/settings.json` and verify that VS Code gives the same results (inline, while editing any Python file in the repo) as running the `mypy` wrapper on the command line, in all the above cases.

Reviewed By: glaringlee, walterddr

Differential Revision: D25977352

Pulled By: samestep

fbshipit-source-id: 4b3a5e8a9071fcad65a19f193bf3dc7dc3ba1b96

mypy-strict.ini

@@ -1,7 +1,10 @@
-# This is a MyPy config file but unlike mypy.ini, it enforces very strict typing
-# rules.  The intention is for this config file to be used to ENFORCE that
-# people are using mypy on codegen files.
-#
+# This is the PyTorch mypy-strict.ini file (note: don't change this line! -
+# test_run_mypy in test/test_type_hints.py uses this string)
+
+# Unlike mypy.ini, it enforces very strict typing rules. The intention is for
+# this config file to be used to ENFORCE that people are using mypy on codegen
+# files.
+
 # For now, only code_template.py and benchmark utils Timer are covered this way
 
 [mypy]
@@ -33,6 +36,7 @@ strict_equality = True
 files = tools/codegen/gen.py,
     tools/autograd/*.py,
     tools/pyi/*.py,
+    torch/testing/_internal/mypy_wrapper.py,
     torch/utils/benchmark/utils/common.py,
     torch/utils/benchmark/utils/timer.py,
     torch/utils/benchmark/utils/valgrind_wrapper/*.py,
@@ -50,6 +54,10 @@ follow_imports = skip
 [mypy-torch.*]
 follow_imports = skip
 
-# Missing stub.
+# Missing stubs.
+
 [mypy-numpy]
 ignore_missing_imports = True
+
+[mypy-mypy.*]
+ignore_missing_imports = True