libstdc++: Add static_assertions to ranges::to adaptor factory [PR112803]

libstdc++: Add static_assertions to ranges::to adaptor factory [PR112803]

The standard requires that we reject attempts to create a ranges::to
adaptor for cv-qualified types and non-class types. Currently we only
diagnose it once the adaptor is used in a pipeline.

This adds static assertions to diagnose it immediately.

libstdc++-v3/ChangeLog:

	PR libstdc++/112803
	* include/std/ranges (ranges::to): Add static assertions to
	enforce Mandates conditions.
	* testsuite/std/ranges/conv/112803.cc: New test.