Update "old" range types

[CaseyCarter]

Description

• array, basic_string, basic_string_view, valarray, and vector (span is not yet implemented) model contiguous_range by defining the nested type iterator_concept to contiguous_iterator_tag in iterator and const_iterator, and specializing pointer_traits for those types (to fulfill contiguous_iterator's std::to_address requirement)

• basic_string_view (Ditto, no span yet) models the exposition-only forwarding-range concept (which indicates that the validity of iterators is not bound to the lifetime of the range) by defining hidden-friend overloads of begin and end that accept rvalues

• Drive-by:

  • mark the _Unfancy internal helper function [[nodiscard]]
  • Remove redundant _Can_begin requirement from std::ranges::_Begin::_Cpo::_Choose

• Add test coverage to devcrt/P0896R4_ranges_range_machinery:

  • tighten up test_std_container:
    • data and cdata reject rvalue arguments since the returned pointer could potentially dangle (contiguous_range codepaths were lacking coverage)
    • the size_type of a standard container can be other than std::size_t when using fancy pointers
    • we should enforce that each container's iterator type models the expected concept
  • Add test coverage to ensure that contiguous standard library containers model contiguous_range even when using an "old" fancy pointer type that does not model contiguous_iterator

Checklist:

• I understand README.md.
• If this is a feature addition, that feature has been voted into the C++
  Working Draft.
• Any code files edited have been processed by clang-format.
• Identifiers in any product code changes are properly _Ugly as per
  https://eel.is/c++draft/lex.name#3.1 .
• Identifiers in test code changes are not _Ugly.
• Test code includes the correct headers as per the Standard, not just
  what happens to compile.
• The STL builds and test harnesses have passed (must be manually verified
  by an STL maintainer before CI is online, leave this unchecked for initial
  submission).
• This change introduces no known ABI breaks (adding members, renaming
  members, adding virtual functions, changing whether a type is an aggregate or
  trivially copyable, etc.). If unsure, leave this box unchecked and ask a
  maintainer for help.

This is a replay of Microsoft-internal pull request 201813.

[StephanTLavavej]

Your commit notes describe "add test coverage", but the tests aren't on GitHub yet. No need to remove, just wanted to mention it. Otherwise looks good.