Enable `HttpRequest.RequestContext`

[twsouthwick]

Summary

HttpRequest.RequestContext is similar to endpoint information. The information here may be able to be exposed in a way that makes this available to code written for System.Web.

In scope

• System.Web.HttpRequest.RequestContext
• System.Web.Routing.RouteData
• System.Web.Routing.IRouteHandler
• System.Web.Routing.RouteValueDictionary

Out of scope

• The System.Web routing system itself; this would just expose data with types from System.Web but gather it from endpoints

Risks / unknowns

• This may start bringing in more than we'd want (especially around the namespace System.Web.Routing). This would need to be explored a bit more.