The C# functions for GetGenericParameters/GetGenericArguments use
Type[], not lists, so we should conform to that.
Also fix the definition of IsGenericTypeDefinition - because it's
possible for a class to be instantiated with all generic parameters.
Because TypesByReferenceIndex can be populated in two places
(Il2CppModel constructor and GetTypeFromVirtualAddress), we need to
avoid generating the same type multiple times.
This patch replaces Il2CppModel.resolveTypeReference by a static
TypeInfo constructor, and simultaneously refactors the TypeInfo
constructors to eliminate duplication between resolveTypeReference and
the original constructors. This will make future refactoring much
easier.
