feat: add mongo init script, use root in app image

mongo-init.js

@@ -0,0 +1,10 @@
+const user = process.env.MONGO_USER
+const password = process.env.MONGO_PASS
+const dbName = process.env.MONGO_DB
+
+db = db.getSiblingDB(dbName)
+db.createUser({
+  user: user,
+  pwd: password,
+  roles: [{ role: 'readWrite', db: dbName }],
+})