Simplify query rules by removing $expand select option

In OData-1105 we added support for simplifying the syntax for selecting multiple fields from a complex type by introducing $select options, consistent with nested expand options. This also allowed us to specify other select options for collections, such as top, skip, count, and filter.

Unfortunately, we also introduced $expand as a nested select option. Providing the ability to expand inside a select provides multiple ways to express the same thing in the same request, requiring rules to validate the combination of nested expands and regular expands that add complexity to the system with no added benefit.