Add scripts for checking that graphql-codegen results in no changes

bin/assert-no-changes.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+git ls-files | xargs md5sum > before.txt
+
+yarn install
+yarn graphql-codegen
+
+git ls-files | xargs md5sum > after.txt
+
+
+diff before.txt after.txt