P2321R2: views::adjacent_transform, views::pairwise_transform

[JMazurkiewicz]

Closes #2252. Implemented features:

• [range.adjacent.transform],
• Feature test macro __cpp_lib_ranges_zip 202110L,
• Relevant parts of LWG-3848 and LWG-3798.

TODO

• Reduce and report Clang bug marked in the code with LLVM-?. Current repro:

  #include <ranges>
  
  auto sum = [](auto... vals) { return (vals + ...); };
  int vals[] = {1, 2, 3, 4, 5};
  auto v = std::views::adjacent_transform<3>(vals, sum);

  There is no need to report this bug, it's been fixed in Clang 16: https://godbolt.org/z/815f371Wc.
• Reduce and report MSVC bug: _Invoke_result_with_repeated_type_impl had to be implemented as a recursive template (using index sequence caused ICE). See DevCom-10302378,
• More tests.

[strega-nil-ms]

one minor request; will push changes.

never mind.

[StephanTLavavej]

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

[StephanTLavavej]

Thanks to you, @cpplearner, and @tylerbrawl, the zip paper is now complete! Thank you all!

😻 🤐 🚀