Add lint for unqualified `type: ignore` (#56290)
Summary:
The other half of https://github.com/pytorch/pytorch/issues/56272.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56290
Test Plan:
CI should pass on the tip of this PR, and we know that the lint works because the following CI runs (before this PR was finished) failed:
- https://github.com/pytorch/pytorch/runs/2384511062
- https://github.com/pytorch/pytorch/actions/runs/765036024
Reviewed By: seemethere
Differential Revision: D27867219
Pulled By: samestep
fbshipit-source-id: e648f07b6822867e70833e23ddafe7fb7eaca235
