More optimizations for contiguous iterators

[AdamBucior]

Changes in this PR:

• Implemented memmove optimization in ranges::copy/move family
• Extended memcpy optimization in ranges::uninitialized_copy/move to non-common ranges
• doing-nothing-for-trivially-destructible-types optimization in ranges::destroy
• optimizations for non-unwrappable contiguous iterators in everything that depends on _Ptr_*_cat
• also corrected a small semantic mistake: _Ptr_copy_cat<move_iterator<*>, *> should derive from _Ptr_move_cat

[CaseyCarter]

Just a few nitpicky things.

[CaseyCarter]

Repeating one comment that was buried in my first review and went unnoticed.

[miscco]

@AdamBucior I think the recommendation was to simply use a 👍 emoji and resolving the comment rather than a reply, when review comments are adopted without change. That helps a lot keeping the inbox clean

[AdamBucior]

BTW this is ready for review

[StephanTLavavej]

Thanks for continuing these performance improvements! I'm going to initially Changelog this under "Dev17" 17.0 Preview 1, but we're going to try to port it (along with C++20 feature work) to VS 2019 16.10 Preview 3. 🚀 🚀 🚀