Add native types under capnp.types for use with ListSchema

test/annotations.capnp

@@ -7,9 +7,11 @@ struct AnnotationStruct {
 annotation test1(*): Text;
 annotation test2(*): AnnotationStruct;
 annotation test3(*): List(AnnotationStruct);
+annotation test4(*): List(UInt16);
 
 $test1("TestFile");
 
 struct TestAnnotationOne $test1("Test") { }
 struct TestAnnotationTwo $test2(test = 100) { }
 struct TestAnnotationThree $test3([(test=100), (test=101)]) { }
+struct TestAnnotationFour $test4([200, 201]) { }