libstdc++: Implement ranges::slide_view from P2442R1

This also implements the LWG 3711 and 3712 changes to slide_view.

libstdc++-v3/ChangeLog:

	* include/std/ranges (__detail::__slide_caches_nothing): Define.
	(__detail::__slide_caches_last): Define.
	(__detail::__slide_caches_first): Define.
	(slide_view): Define.
	(enable_borrowed_range<slide_view>): Define.
	(slide_view::_Iterator): Define.
	(slide_view::_Sentinel): Define.
	(views::__detail::__can_slide_view): Define.
	(views::_Slide, views::slide): Define.
	* testsuite/std/ranges/adaptors/slide/1.cc: New test.