Expunge TensorId from all DispatchKey names. (#36240)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36240
It's annoying, historical, and unnecessary (enum class is already
namespaced). I did this codemod with:
```
git grep -l 'CPUTensorId' | xargs sed -i 's/CPUTensorId/CPU/g'
git grep -l 'CUDATensorId' | xargs sed -i 's/CUDATensorId/CUDA/g'
git grep -l 'VariableTensorId' | xargs sed -i 's/VariableTensorId/Autograd/g'
git grep -l 'HIPTensorId' | xargs sed -i 's/HIPTensorId/HIP/g'
git grep -l 'MSNPUTensorId' | xargs sed -i 's/MSNPUTensorId/MSNPU/g'
git grep -l 'XLATensorId' | xargs sed -i 's/XLATensorId/XLA/g'
git grep -l 'PrivateUse1_TensorId' | xargs sed -i 's/PrivateUse1_TensorId/PrivateUse1/g'
git grep -l 'PrivateUse2_TensorId' | xargs sed -i 's/PrivateUse2_TensorId/PrivateUse2/g'
git grep -l 'PrivateUse3_TensorId' | xargs sed -i 's/PrivateUse3_TensorId/PrivateUse3/g'
git grep -l 'AutocastTensorId' | xargs sed -i 's/AutocastTensorId/Autocast/g'
git grep -l '_PreAutogradTensorId' | xargs sed -i 's/_PreAutogradTensorId/_PreAutograd/g'
git grep -l 'TESTING_ONLY_GenericWrapperTensorId' | xargs sed -i 's/TESTING_ONLY_GenericWrapperTensorId/TESTING_ONLY_GenericWrapper/g'
git grep -l 'TESTING_ONLY_GenericModeTensorId' | xargs sed -i 's/TESTING_ONLY_GenericModeTensorId/TESTING_ONLY_GenericMode/g'
```
Then I did a git grep for remaining TensorId occurrences, and manually
killed those (mostly in codegen, and some docs that needed updating).
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Differential Revision: D20929255
Pulled By: ezyang
fbshipit-source-id: dc371b6aa6e6ea7c0a5660137c14debde806a09d
