Fix for bad ordering with $skiptoken enabled and $orderby=... desc

[orty]

Hi,

We just encountered an issue related to the EnableLowerCamelCase feature, in a scenario where we issue a query with pagination enabled (using $skiptoken) and a descending $orderby.

The issue is situated here :

AspNetCoreOData/src/Microsoft.AspNetCore.OData/Query/Query/DefaultSkipTokenHandler.cs

Line 315 in fce1c61

if (directionMap.ContainsKey(key) && directionMap[key] == OrderByDirection.Descending)

the keys in the dictionary do not match with the key variable because of the different casing. The same is happening with aliased properties.
It results in a false 'false' evaluation of the if condition, and the else branch of the if is evaluated, generating a wrong predicate on SQL side (ascending instead of descending)

The issue can be fixed here :

AspNetCoreOData/src/Microsoft.AspNetCore.OData/Query/Query/DefaultSkipTokenHandler.cs

Line 264 in fce1c61

orderByNodes.OfType<OrderByPropertyNode>().ToDictionary(node => node.Property.Name, node => node.Direction);

by providing the proper keys to the directionMap dictionary.