Restructure AggregationBinder

[KenitoInc]

The main changes:

• Wrap the required AggregationBinder properties in QueryBinderContext
• Make the AggregationBinder implement IAggregationBinder
• Inject AggregationBinder as an implementation of IAggregationBinder
• Make BindSelect and BindGroupBy methods virtual.
• Remove support for EFClassic

Make AggregationBinder public and extensible

public class AggregationBinder : QueryBinder, IAggregationBinder
{
    public virtual Expression BindSelect(TransformationNode transformationNode, QueryBinderContext context)
    {
    }

    public virtual Expression BindGroupBy(TransformationNode transformationNode, QueryBinderContext context)
    {
    }
}