feat(shape): remove redundant carrying of a type's runtime type

[sam-goodwin]

// replace this
class ArrayType<T extends Type<V>, V> implements Type<V[]>
// with
class ArrayType<T extends Type<any>> implements Type<RuntimeType<T>[]>

// it makes our types easier to work with. this:
ArrayType<StringType> = 
// instead of this:
ArrayType<StringType, string>