Setup node-cache

increase performance of queries by caching user info from JWT
Would also remove a lot of redundant code like
```js
    if (!decodedToken || !decodedToken.sub) {
      return new GraphQLError('Missing fields in the Auth Token');
    }
    const { sub } = decodedToken;
    const userFromDB = await UserModel.findOne({ authProviderID: sub }).setOptions({ sanitizeFilter: true }).exec();
```