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

* adds code generation fuzzer target.

* add buffer verification

* add table verification in codegen fuzzer

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

tests/fuzzer/seed_codegen/empty_namespace

@@ -0,0 +1,6 @@
+table Person {
+  name:string;
+  age:int;
+}
+
+root_type Person;