After using namespaced kubernetes client, we will not need to always set the namespace when creating kubernetes resources(e.g. deployment, pods, configmap, watch, etc.).

Address comments: Update the unit test to verify the configmap watch is created in appropriate namespace

This closes #14570.

[FLINK-18971][kubernetes] Support to mount kerberos conf as ConfigMap and Keytab as Secrete in Kubernetes

This closes #12455.

[hotfix] Add setupFlinkConfig to KubernetesTestBase to make sure flinkConfig is always setup before used

This closes #11675.

[FLINK-15790][k8s] Make some interfaces in FlinkKubeClient asynchronous which potentially blocks the execution of RpcEndpoint's main thread

The interfaces in FlinkKubeClient will be called both in Client and ResourceManager. To avoid potentially blocking the execution of RpcEndpoint's main thread, these interfaces #createTaskManagerPod, #stopPod should be implemented asynchronously.

This closes #11427.

This closes #11489 .

This closes #11415 .

[FLINK-16494][k8s] Switch to enum type for config option KubernetesConfigOptions.CONTAINER_IMAGE_PULL_POLICY

This closes #11406 .

[FLINK-16194][k8s] Introduce Java command decorator for the main Container of the JobManager and the TaskManger Pod

- make KubernetesTestBase contains only the common logic of the client-side and cluster-side
- remove some unnecessary methods of getting kube client and mocking Service's ADD event

The config option "containerized.master.env." could be used to set the environment variables. For example, containerized.master.env.LD_LIBRARY_PATH: "/usr/lib/native".

This closes #10788.

[hotfix][kubernetes] Let creating Flink master deployment and taskmanager pod respect user defined config

BlobServerOptions.PORT and TaskManagerOptions.RPC_PORT need to be respected.

The Fabric8FlinkKubeClient will be used to interact with Kubernetes API server to create/delete resources and get the status. The decorators will be used to build the complete Kubernetes resource description.

This closes #9965 .