[FEATURE] Add ability to specify nodePort

[Moep90]

In my current usecase I want to add a service of type NodePort. Currently this is possible but without the ability to specify the nodePort itself.
So if I create a service of type NodePort I get a service with a (by kubernetes) randomly added NodePort between 30000-32767

Official docs:
https://kubernetes.io/docs/concepts/services-networking/service/#nodeport

Expected input:

  components:
    myapp:
[...]
      ports:
        my-service:
          service_port: 80
          container_port: 80
          node_port: 30007

expected outcome:

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  type: NodePort
  selector:
    app: myapp
  ports:
      # By default and for convenience, the `targetPort` is set to the same value as the `port` field.
    - port: 80
      targetPort: 80
      # Optional field
      # By default and for convenience, the Kubernetes control plane will allocate a port from a range (default: 30000-32767)
      nodePort: 30007

The old libsonnet generator has it:

kapitan-reference/lib/kap.libsonnet

Line 132 in 92b13dc

nodePort: utils.objectGet(self.port_info, 'node_port'),

The new kadet generator doesn't honor the node_port

kapitan-reference/components/generators/kubernetes/__init__.py

Lines 275 to 293 in cfe6f51

	all_ports = [component.ports] + [container.ports for container in component.additional_containers.values()
	if 'ports' in container]
	exposed_ports = {}
	for port in all_ports:
	for port_name in port.keys():
	if not service_spec.expose_ports or port_name in service_spec.expose_ports:
	exposed_ports.update(port)
	for port_name in sorted(exposed_ports):
	port_spec = exposed_ports[port_name]
	if 'service_port' in port_spec:
	self.root.spec.ports += [{
	'name': port_name,
	'port': port_spec.service_port,
	'targetPort': port_name,
	'protocol': port_spec.get('protocol', 'TCP')
	}]

So I exceeded my knowledge and time to solve this issue myself 👎