Adding custom non-batched return types for non-batch calls

[assafi]

An update to v4.0.0 which has not been published yet (hence the same version number).
Adding custom non-batched return types for non-batch calls simplifying the callee code.

Previously, the non-batch methods would send a single document for analysis but return a batch response that can only contain a single document. Instead, we now return a single response from these methods and unwrap the list for you. The same is done for any potential errors and statistics responses.

Previously:

var result = client.DetectLanguage("This is a document written in English.");

// Printing detected languages
Console.WriteLine($"Language: {result.documents[0].DetectedLanguages[0].Name}");

And now:

var result = client.DetectLanguage("This is a document written in English.");

// Printing detected languages
Console.WriteLine($"Language: {result.DetectedLanguages[0].Name}");

This is a simplification over a batch service REST API that hasn't changed. Will be mainly used for example/documentation purposes.

[assafi]

Please refer to this recent PR for v4.0.0 changes.

[assafi]

@AlexGhiondea / @shahabhijeet - Could you please review?

[AlexGhiondea]

@assafi I approved this PR. Going forward, would you mind adding more information/context to the PR? It helps to review the code knowing what motivated the change :).

[assafi]

@AlexGhiondea Thanks. I elaborated a bit more on the PR description.