Add support for .Destructure.AsScalar(Type scalarType)

[tsimbalar]

Fixes #115

• Support method arguments of type Type by converting from the type's qualified name
• Add support for (non-extension) method Destructure.AsScalar
• Add test to check that custom extension methods Destructure.XXX() can properly be invoked
• Refactor ConfigurationReader by extracting all the surrogate method handling to a separate class

[MV10]

@tsimbalar love that change to move the Surrogate methods to their own home. That ConfigurationReader class was getting a bit tangled-up...