libstdc++: Define std::ranges::to for C++23 (P1206R7) [PR111055]

libstdc++: Define std::ranges::to for C++23 (P1206R7) [PR111055]

This adds the std::ranges::to functions for C++23. The rest of P1206R7
is not yet implemented, i.e. the new constructors taking the
std::from_range tag, and the new insert_range, assign_range, etc. member
functions. std::ranges::to works with the standard containers even
without the new constructors, so this is useful immediately.

The __cpp_lib_ranges_to_container feature test macro can be defined now,
because that only indicates support for the changes in <ranges>, which
are implemented by this patch. The __cpp_lib_containers_ranges macro
will be defined once all containers support the new member functions.

libstdc++-v3/ChangeLog:

	PR libstdc++/111055
	* include/bits/ranges_base.h (from_range_t): Define new tag
	type.
	(from_range): Define new tag object.
	* include/bits/version.def (ranges_to_container): Define.
	* include/bits/version.h: Regenerate.
	* include/std/ranges (ranges::to): Define.
	* testsuite/std/ranges/conv/1.cc: New test.
	* testsuite/std/ranges/conv/2_neg.cc: New test.
	* testsuite/std/ranges/conv/version.cc: New test.