Add hint support

[EliSadaka]

Summary

Adds support for the hint param in find queries: https://docs.mongodb.com/manual/reference/method/cursor.hint/

Other Information

Usage examples:

const query = { userId: 12345 };
const hint = { userId: 1 };
users.find({ query, hint }).then( ... );

const query = { userId: 12345 };
const hint = "index_name";
users.find({ query, hint }).then( ... );

[daffl]

Great, thank you!