`<any>` cleanup:
* Prefer variable templates to class templates
* Prefer `if constexpr` to tag dispatch
* Function pointers may be `noexcept` in C++17
* Remove the layer of "symbolic member name" functions to improve debug codegen
* Conventionally use `enable_if_t<conjunction_v<meow, woof>` instead of `enable_if_t<meow::value && woof::value>`
* Apply `_NODISCARD` and `noexcept` to internal functions as appropriate
* Allow overaligned types, which are properly handled by the `_Big` representation
Resolves [DevCom-724444](https://developercommunity.visualstudio.com/content/problem/724444/meow.html).