chore: Embed unit test data (#1812)

* Embed unit test data

* Add testdata

Co-authored-by: anqiansong <anqiansong@bytedance.com>

tools/goctl/api/parser/testdata/test.api

@@ -0,0 +1,18 @@
+    // syntax doc
+    syntax = "v1" // syntax comment
+
+    // type doc
+    type Request {
+        Name string `path:"name,options=you|me"`
+    }
+
+    type Response {
+        Message string `json:"message"`
+    }
+
+    // service doc
+    service greet-api {
+        // handler doc
+        @handler GreetHandler // handler comment
+        get /from/:name(Request) returns (Response);
+    }