Use deltatoken for delta snippets in dotnet

[andrueastman]

Closes #279
This PR is part of #1673.

It updates the snippet generation for C# involving delta queries to use the raw request url in the request builder constructor as the url.

Therefore an example snippet
GET https://graph.microsoft.com/v1.0/users/delta?$deltatoken=oEcOySpF_hWYmTIUZBOIfPzcwisr_rPe8o9M54L45qEXQGmvQC6T2dbL-9O7nSU-njKhFiGlAZqewNAThmCVnNxqPu5gOBegrm1CaVZ-ZtFZ2tPOAO98OD9y0ao460

will result in the snippet below.

var graphClient = new GraphServiceClient(requestAdapter);

var deltaRequestBuilder = new Microsoft.Graph.Users.Delta.DeltaRequestBuilder("https://graph.microsoft.com/v1.0/users/delta?$deltatoken=oEcOySpF_hWYmTIUZBOIfPzcwisr_rPe8o9M54L45qEXQGmvQC6T2dbL-9O7nSU-njKhFiGlAZqewNAThmCVnNxqPu5gOBegrm1CaVZ-ZtFZ2tPOAO98OD9y0ao460", graphClient.RequestAdapter);
var result = await deltaRequestBuilder.GetAsync();

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