Allow to set HttpClient when creating the client

[omerlh]

Currently, there is overload that let you set the HttpClient (for example, if you want to override the default timeout) and use KubernetesClientConfiguration. There is such a constructor on the generated Kubernetes object - but it doesn't accept configuration.

[ajamrozek]

After you construct your client. You can set the HttpClient property properties.

var client = new Kubernetes(k8sClientConfig);
client.HttpClient.Timeout = new TimeSpan(0, 0, 0, 30);

[winromulus]

I would also like to have this option so I can use the HttpClientFactory.
Currently I'm suffering from the DNS update issue of the standard client.

[DavidParks8]

I want to use HttpClientFactory as well, and the change was fairly small, all things considered. Take a look at #302.