* Add properties to ModuleFile which holds information from the control
block.
* 'ExtendedValidationInfo' parameter for 'ModuleFileSharedCore::load()'
cannot be 'nullptr'. Make it non-defaulted Rvalue reference.
'ModuleInterfacePath' is passed as 'StringRef' that memory used to
reside in ASTContext. But 'ModuleFileSharedCore' should be 'ASTContext'
independent. So copy it using its own allocator.
The difference with `ModuleFile` is that `ModuleFileSharedCore` provides immutable data and is independent of a particular ASTContext.
It is designed to be able to be shared across multiple `ModuleFile`s of different `ASTContext`s in a thread-safe manner.
