[aot_inductor] move CppWrapperCodeGen into a separate file (#119871)
This reverts commit d8e319a961bb872027f0abdc413d6beb7502ac9b.
Differential Revision: [D53817853](https://our.internmc.facebook.com/intern/diff/D53817853)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119871
Approved by: https://github.com/albanD, https://github.com/khabinov
ghstack dependencies: #119870
