[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/enum_test

@@ -0,0 +1,8 @@
+enum Color:byte { Red, Green, Blue }
+
+table Item {
+  name:string;
+  color:Color;
+}
+
+root_type Item;