feat(model+query): support options parameter for distinct()

[vkarpov15]

Fix #8006

Summary

Make it easier to use distinct() with transactions, so you don't need to chain setOptions(). distinct() looks to be the only query function where you can't pass in options.

Examples

[hasezoey]

LGTM, but the options parameter still needs to be added to the query types (currently only in the model's types) and a similar test to using options parameter for distinct on query should likely be in for Model too, or is the transaction test enough?

As a note, the Model.distinct and Query.prototype.distinct have differing options checks, is this intentional?

[vkarpov15]

Thanks for the suggestions @hasezoey , I've implemented them both. Added options param to query distinct() types and removed the typeof options === 'object' check in Query.prototype.distinct (and countDocuments() + estimatedDocumentCount() for consistency)