Removed any hint of an implementation of the AST. I will leave this to the
guys who know what they are doing. For now, I'll just specify the interfaces and JUnits that show how they should behave.
Fix for PR 60307 [Templates] Template parameter qualified types not supported
Added new symbol type: UndefinedTemplateSymbol that represents template paramater qualified types. At instantiation the unknown types are replaced with the real ones.