Obsolete ASP.NET WebHooks

ASP.NET WebHooks has very low usage and is not an active area of investment. In an effort to reduce our support burden, we're proposing to obsolete and archive ASP.NET WebHooks. The Azure Functions dependency on ASP.NET WebHooks has already been [deprecated](https://azure.microsoft.com/en-us/updates?id=support-for-the-1x-version-of-azure-functions-ends-14-september-2026).