Enhanced hidl-gen support for generating vts files.

*Support callflow from mehtod annotations.
*Support inheritance for interfaces and types.
*Support Array and Union type.

b/30762234

Change-Id: I059b780d6362a557bb9cfd70d6c5ec0e73916ce3
diff --git a/Interface.h b/Interface.h
index d825122..b46501e 100644
--- a/Interface.h
+++ b/Interface.h
@@ -47,7 +47,10 @@
             const std::string &argName,
             bool isReader) const override;
 
-    status_t emitVtsArgumentType(Formatter &out) const override;
+    status_t emitVtsAttributeType(Formatter &out) const override;
+
+    status_t emitVtsAttributeDeclaration(Formatter &out) const;
+    status_t emitVtsMethodDeclaration(Formatter &out) const;
 
     bool isJavaCompatible() const override;