[metacling] Add test against #6578 and ctor access
[metacling] Add test against #6578 and ctor access

olifre/root,root-mirror/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root