Revisit Policy status, policy mode status and conditions and refactor the policy subreconciler

[fabriziosestito]

Status

At the time of writing, the policy status is composed by [PolicyModeStatus](https://github.com/kubewarden/kubewarden-controller/blob/a331d8d2d4ccd26396935fd9333118c85185280a/api/policies/v1/policy.go#L31) and [PolicyStatusEnum](https://github.com/kubewarden/kubewarden-controller/blob/a331d8d2d4ccd26396935fd9333118c85185280a/api/policies/v1/policy.go#L11). Unfortunately this adds complexity in the reconciliation loop and it could be ambiguous for the user.
Instead, we could merge PolicyModeStatus with PolicyStatusEnum having two different final active states PolicyStatusActiveMonitor and PolicyStatusActiveProtect.

Condition

Also, we could revisit the PolicyConditionType. We could either remove them or refactor them to be more explicit. See: https://maelvls.dev/kubernetes-conditions/

Reconciler

The policy subreconciler reconciliation loop could be simplified using the new statuses/conditions.

• we could remove the reconcilePolicy and refactor the setPolicyStatus methods, as the first could be part of the reconcile method and the second one does not set the policy status, but it changes the policy mode status instead. The status change is also spread in the reconcilePolicy and reconcile methods.
• investigate why we need to store the reconcileErr and return it after the status update.

This is related to: #743, #616

[fabriziosestito]

Also we need to investigate this error

2024-07-19T15:03:43+02:00     ERROR   Reconciler error        {"controller": "policyserver", "controllerGroup": "policies.kubewarden.io", "controllerKind": "PolicyServer", "PolicyServer": {"name":"policy-server-u0y4ypm0"}, "namespace": "", "name": "policy-server-u0y4ypm0", "reconcileID": "44def5e9-383a-4e85-9ed3-770d384c7ac2", "error": "update policy server status error: Operation cannot be fulfilled on policyservers.policies.kubewarden.io \"policy-server-u0y4ypm0\": the object has been modified; please apply your changes to the latest version and try again"}
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler
        /home/lain/.asdf/installs/golang/1.22.3/packages/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:324
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem
        /home/lain/.asdf/installs/golang/1.22.3/packages/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:261
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2
        /home/lain/.asdf/installs/golang/1.22.3/packages/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:222

which might be related.