Add AddJsonOptions to KubernetesClientConfiguration and KubernetesJson (#1257)

* Use camelCase policy when serializing enums

* Revert "Use camelCase policy when serializing enums"

This reverts commit 467f49d8734bcbd6aabb87447fbd7d21840c4c48.

* Add jonSerializerOptions to GenericClient

* Add jsonSerializerOptions param

* Revert pass deserialization options in GenericClient

* Add JsonSerializerOptions to KubernetesClientConfiguration

* Use user JsonSerializerOptions in SendRequest and CreateResultAsync

* Improve comment

* Remove JsonSerializerOptions

* Cosmetic

* Add AddJsonOptions

* Fix example

* Fix test

* Add test

* Add summary

* Improve summary

* Remove configure from Kubernetes ctor and tests

* Add AddJsonOptions to config and test

* Support per client json serializer options

* Add ConfigureAwait for tests

* Check for nullargument

examples/prometheus/Prometheus.cs

@@ -1,7 +1,6 @@
 using k8s;
 using Prometheus;
 using System;
-using System.Net.Http;
 using System.Threading;
 
 namespace prom
@@ -12,7 +11,7 @@ namespace prom
         {
             var config = KubernetesClientConfiguration.BuildDefaultConfig();
             var handler = new PrometheusHandler();
-            IKubernetes client = new Kubernetes(config, new DelegatingHandler[] { handler });
+            IKubernetes client = new Kubernetes(config, handler);
 
             var server = new MetricServer(hostname: "localhost", port: 1234);
             server.Start();