[csharp][netcore-httpclient] Refactor of constructors

Created by: lucamazzanti

It tries to reduce the number of constructors introduced in previous PR. Related to: #9060 (closed), #9085

Refactor on constructors

In the previous PM I created too much constructors. This is an emprovement to reduce them:

1. I kept the HttpClient service as first parameter when available in signature
2. Then the configurations
3. Then the optional HttpClientHandler

With this PM we have in ApliClient:

1. ctor()
2. ctor(string basePath)
3. ctor(HttpClient client, HttpClientHandler handler = null)
4. ctor(HttpClient client, string basePath, HttpClientHandler handler = null)

(point 1-2 marked as obsolete) and in ApiClass:

1. ctor()
2. ctor(string basePath)
3. ctor(Configuration configuration)
4. ctor(HttpClient client, HttpClientHandler handler = null)
5. ctor(HttpClient client, string basePath, HttpClientHandler handler = null)
6. ctor(HttpClient client, Configuration configuration, HttpClientHandler handler = null)
7. ctor(ISynchronousClient client, IAsynchronousClient asyncClient, IReadableConfiguration configuration)

(point 1-3 marked as obsolete)

Obsolete constructors

Marked constructors without the explicit HttpClient parameter as obsolete.

Spaces and indentations

Unfortunatly I had a different setup for spaces and indentations on my IDE and I did not see it on my local versioning tool. So the changes have some spaces because I fixed my previous PM, moving some tabs to 4 spaces. They are a few lines not so much, but this is why you see some noise in the diffs, its a fix to keep and I will avoid it at all in the future.

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