types(model): fix type of options of Model.aggregate

[ghost91-]

Summary

This change adjusts the type of the options parameter of Model.aggregate to be the AggregateOptions type from mongoose, instead of the one from mongodb. The aggregate method just passes this parameter on to Aggregate.option, which is already typed to accept the AggregateOptions type from mongoose, so this seems like the correct choice.

The 2 types mostly seem to be compatible anyways, but there is a small inconsistency that makes them incompatible: mongodb.AggregateOptions specifies that the session property may be a ClientSession, or undefined (but not null), while the AggregateOptions type from mongoose also allows null. So maybe that also should simply be aligned.

[vkarpov15]

This should work fine, but to reduce the risk of any backwards breaking changes, can we change AggregateOptions to something like the following?

interface AggregateOptions extends Omit<mongodb.AggregateOptions, 'session'>, SessionOption {
    [key: string]: any;
  }

That seems to work fine, and makes it so that there's no chance we missed an option from mongodb.AggregateOptions.

[ghost91-]

I have incorporated the suggestion. Before doing so, I have manually verified that there are no differences between the 2 AggregateOptions types, aside from allowing null as the session property.

[vkarpov15]

Thanks 👍

[vkarpov15]

Thanks 👍