Also, improve tests for std::destroy and std::destroy_n so that they
check for array support.
These changes are part of http://wg21.link/p0896 (the One Ranges proposal).
Differential Revision: https://reviews.llvm.org/D106916
Moves:
* `std::move`, `std::forward`, `std::declval`, and `std::swap` into
`__utility/${FUNCTION_NAME}`.
* `std::swap_ranges` and `std::iter_swap` into
`__algorithm/${FUNCTION_NAME}`
Differential Revision: https://reviews.llvm.org/D103734
Louis Dionne