Cleanups 1: Comments and formatting

[StephanTLavavej]

• Detach comments.
  • This isn't attempting to be a global cleanup. Many of these will prevent the addition of _EXPORT_STD from causing wrapping, some fix wrapping that's already bad, some are for local consistency.
• <string>: Remove unnecessary comments for to_string(), to_wstring(), and stoi() etc. - they're just repeating the function names.
  • A few (like stold()) would also cause wrapping with _EXPORT_STD.
• <cstddef>: Remove SHOUTY RELICS and unnecessary comments, detach remaining comments.
• <type_traits>: Comment _Refwrap_ctor_fun as // not defined.
• <random>: Remove extra newline.
• <random>: Unwrap string literals for assertions.
• <xutility>: Shrink clang-format off region, add newline after declaring ranges::less.

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.