Inductor cpp wrapper: support dynamic shapes (#97965)
1. Fixed dynamic shapes support in cpp_wrapper
- fixed the cpp codegen of `size()` and `stride()`
- fixed the cpp codegen of `ShapeAsConstantBuffer`
- changed to use `cexpr` instead of `pexpr` in the cpp codegen of the `sizevar`
2. Enabled dynamic shapes tests for cpp_wrapper
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97965
Approved by: https://github.com/jgong5, https://github.com/jansel
