add schema for tests

test/test_structs_sequence.capnp

@@ -0,0 +1,27 @@
+@0x9dafb673e5609df6;
+
+
+enum FruitId {
+  apple @0;
+  banana @1;
+  cherry @2;
+}
+
+struct UnknownFruit {
+  fruitId @0: FruitId;
+}
+
+struct Apple {
+  fruitId @0: FruitId;
+  color @1: Text;
+}
+
+struct Banana {
+  fruitId @0: FruitId;
+  length @1: Float32;
+}
+
+struct Cherry {
+  fruitId @0: FruitId;
+  sweetness @1: UInt8;
+}