[MPS][BE] `std::is_same::value` -> `std::is_same_v` (#100975)
PyTorch is C++17 project, so let's use some C++17 features.
I.e. `s/std::is_same<X, Y>::value/std::is_same_v<X, Y>`
And use `if constexpr` in few places when this construct is used.
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### <samp>🤖 Generated by Copilot at 7b7683f</samp>
> _We're sailing on the sea of code, we're making it more neat_
> _We're using `is_same_v` and `if constexpr` to keep it sweet_
> _We're refactoring the range tensor logic, we're avoiding duplication_
> _We're heaving on the ropes of `Distributions.mm`, on the count of three, with elation_
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100975
Approved by: https://github.com/jeanschmidt, https://github.com/albanD, https://github.com/kulinseth, https://github.com/Skylion007
