Feature: Generic Context for types

[Washi1337]

Summary:
Generic types and methods use instances of the GenericParameterSignature to reference type parameters. When instantiated, these signatures are at runtime replaced with the type arguments of the type or method instantiation. Therefore, for better analysis of the .NET metadata, it can is useful to obtain the type argument as was provided in the instantiation context.

Suggested syntax:

var context = new GenericContext(genericTypeInstance, genericMethodInstance);

GenericParameterSignature parameter = ...;
TypeSignature typeArgument = context.GetTypeArgument(parameter);