Add Azure App Services middleware

[AButler]

Azure App Services strips encoded path delimiters (%2F) before sending the request to the underlying server and this cannot currently be disabled. They do add a header that contains the original URL so this middleware restores back the request URL.

For more information see dotnet/aspnetcore#40532
and Azure/azure-functions-host#9402

[JJong-nl]

One issue..
The X-Waws-Unencoded-Url contains the PathAndQuery.
The Request.Path must be set with only the AbsolutePath.

if (context.Request.Headers.TryGetValue(UnencodedUrlHeaderName, out var unencodedUrlValue) && unencodedUrlValue.Any())
{
    var uri = new Uri($"https://fake.url{unencodedUrlValue.First()}");
    context.Request.Path = new PathString(uri.AbsolutePath);
}