[fuzzer] Adds code generation target. (#8795)

* adds code generation fuzzer target.

* add buffer verification

* add table verification in codegen fuzzer

---------

Co-authored-by: Björn Harrtell <bjornharrtell@users.noreply.github.com>

tests/fuzzer/seed_codegen/complex_schema

@@ -0,0 +1,24 @@
+namespace Example;
+
+enum Status:byte { Active, Inactive, Pending }
+
+struct Point {
+  x:int;
+  y:int;
+}
+
+table User {
+  id:uint;
+  name:string;
+  points:[Point];
+  status:Status = Active;
+  metadata:[string];
+}
+
+table Group {
+  name:string;
+  users:[User];
+  leader:User;
+}
+
+root_type Group;