CountDescriptor.Query IQueryContainer support

[JamieDixon]

Presently, SearchDescriptor.Query has an overload that takes an IQueryContainer.

It would be useful if CountDescriptor.Query also had an overload accepting an IQueryContainer.

This would allow us to pass the same incoming parameters to either method as required without the need to handle CountDescriptor.Query as a special case.

[gmarz]

Agreed, this would be useful. Just thinking that if we did this, we'd have to be consistent and do the same for everywhere we have a Query()...

[Mpdreamz]

Taking this on board because it was super easy to add, on our 2.0 branch we are making an effort in normalizing this across all descriptors.