Refactor PortForwardService to use Kubernetes Client Port Forwarding instead of kubectl binary

[rohanKanojia]

Right now PortForwardService which is used in k8s:debug goal is just executing command kubectl port-forward port.. . This works but won't work when kubectl or oc binary is not available on system.

https://github.com/eclipse/jkube/blob/9e3d67371e8c12bc8aa6288acacc83d1f796ea96/jkube-kit/config/service/src/main/java/org/eclipse/jkube/kit/config/service/PortForwardService.java#L227-L240

We should refactor it to use Fabric8 Kubernetes Client instead. Here is an example, PortForwardExample:

client.pods().inNamespace("default").withName("testpod").portForward(containerPort, 8080);

[manusa]

Following are conclusions of the sync review:

• Methods in services should be private by default.
• addPorts function should have no side-effects
• PortForward + DebugService should be considered with an API vision and not just a MojoExecution. SIGTERM as the mechanism to stop the forward should only be considered only at the Mojo level.
• Locking mechanism is incomplete, should be refactored (see next section)

High level view of PortForward/Debug mode:

Conditions for port forward to work:

• Application is deployed (There is a Deployment/DeploymentConfig/*Controller) in the Cluster
• Deployment has been modified to enable the environment JAVA_ENABLE_DEBUG=true variable (JAVA_DEBUG_SUSPEND=false)
• A new Pod has been scheduled for the updated deployment
• The Pod is ready and running

Before port forwarding

• If debug is invoked with no existent deployment, a message should warn the user, port forwarding shouldn't start
• If any of the other conditions is not matched before starting the forwarding, but deployment exists, we should take care of everything (showing messages to user) and fix it. Once all conditions are green, port forwarding should start.
• Thread execution should be locked with a monitor that guarantees port forwarding conditions are met

During port forwarding

• If any condition reverts/breaks (Pod/Container dies, Deployment is changed/removes, etc.) PortForwarding should stop and user should be informed.