[cxxmodules] Teach TCling::RegisterModule to work with real module files.
[cxxmodules] Teach TCling::RegisterModule to work with real module files.

When we load a library, during its static intialization it calls
TCling::RegisterModule to make ROOT's runtime aware of that load. Regular
ROOT also will do some header parsing to add the minimal infrastructure
in place for cling to be able to call into that library.

C++ modules define away the need to parse. This patch intends to skip all
parsing at this stage and fix recursive parsing issues for C++ modules.

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