CPP1111 — Relax constructor argument rules

Currently the std::array doesn't have an efficient move constructor, passing an array by value to the constructor of a valuetype/struct isn't efficient. Instead of adding an exception to the spec we propose to relax the spec so that it just mentions that the constructor must be there, but not that arguments have to be passed by value, that is up to the implementor to decide

We remove the restriction that the arguments have to be passed by value to the
constructor of a structured type. This is a way implementations can deliver optimizations
if needed. This change will not impact any user code in terms of portability