BREAKING CHANGE: stop using mquery for updateX(), deleteX(), sort(), always convert sort args to objects

[vkarpov15]

Re: #13617

Summary

Unfortunately there's a lot of functionality duplicated between mongoose and mquery, so with #13617 we're moving towards moving this logic into mongoose for easier maintenance. The big change in this PR is sort(): we've moved sort handling into Mongoose, and we're making options.sort always an object. We're now converting .sort([['a', 1]]) into .sort({ a: 1 }), rather than leaving it as [['a', 1]] under the hood. Keeping entries-style syntax internally is not necessary post ES2015, key order is still maintained, and that removes the need for us to handle edge cases like .sort([['a', 1]]).sort({ b: 1 }).

Examples

[AbdelrahmanHafez]

LGTM.
I would've expected some require('mquery') to be removed somewhere, along with its removal from package.json, though.

[hasezoey]

I would've expected some require('mquery') to be removed somewhere, along with its removal from package.json, though.

to my understanding this PR is only for update, delete and sort, but mquery is used in some more places, mainly the mquery.canMerge function and also Query.prototype is new mquery() (and Query.base)

[vkarpov15]

Yeah there are still a few places where we use mquery, most notably for chaining for geo operators. But this PR is mostly just to remove mquery from updateX(), deleteX() and sort(). Those are the most heavily used pieces of code where we still rely on mquery.