fix: allow calling Model.aggregate() with options

[amitbeck]

Summary

I want Mongoose to support passing options to Model.aggregate() and to not have to call Aggregate.option() manually in a separate operation.

Examples

Until now:

// error
Model.aggregate([ /* pipeline */], { allowDiskUse: true }).exec() // Callback must be a function, got [object Object]

// workaround, requires 2 separate operations including storing the `Aggregate` instance as variable
const aggregate = Model.aggregate([ /* pipeline */]);
await aggregate.option({ allowDiskUse: true }).exec();

After this PR:

Model.aggregate([ /* pipeline */], { allowDiskUse: true }).exec() // works

[vkarpov15]

Quick comment re: TS, but otherwise LGTM

[vkarpov15]

I'm pretty sure this will cause a TS error because a mandatory param can't follow an optional param. We'd need to make options required here, and add a separate overload for aggregate(pipeline, cb)

[amitbeck]

Wow I can't believe I actually didn't notice this lol

[amitbeck]

@vkarpov15 thanks for the fix, funny that I missed this.