Remove generated_unboxing_wrappers and setManuallyBoxedKernel (#49251)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49251
Since all ops are c10-full and use templated unboxing now, we don't need to codegenerate any unboxing logic anymore.
Since this codegen was the only code using setManuallyBoxedKernel, we can also remove that functionality from KernelFunction, OperatorEntry and Dispatcher.
ghstack-source-id: 119450486
Test Plan: waitforsandcastle
Reviewed By: ezyang
Differential Revision: D25502865
fbshipit-source-id: 49d009df159fda4be41bd02457d4427e6e638c10
