Implement observedGeneration in order to compare with standard generation property

[tolko]

Is your feature request related to a problem? Please describe.
When observing k8s resource (ArgoCD application) during the update of the values we get two events fired.

Event source is:

apiVersion: argoproj.io/v1alpha1
kind: EventSource
metadata:
  name: resource
spec:
  template:
    serviceAccountName: argo-events-sa 
  resource:
    example:
      namespace: argocd
      group: argoproj.io
      version: v1alpha1
      resource: applications
      eventTypes:
        - UPDATE
      filter:
        fields:
          - key: metadata.name
            operation: ==
            value: ing

sensor is:

apiVersion: argoproj.io/v1alpha1
kind: Sensor
metadata:
  name: resource
spec:
  template:
    serviceAccountName: argo-events-sa
  dependencies:
    - name: test-test
      eventSourceName: resource
      eventName: example
      filters:
        data:
          - path: body.status.health.status
            type: string
            value:
              - Healthy
          - path: body.status.sync.status
            type: string
            value:
              - Synced
          - path: body.status.operationState.phase
            type: string
            value:
              - Succeeded
          
  triggers:
    - template:
        name: webhook-pod-trigger
        k8s:
          group: ""
          version: v1
          resource: pods
          operation: create
          source:
            resource:
              apiVersion: v1
              kind: Pod
              metadata:
                generateName: hello-world-
              spec:
                containers:
                  - name: hello-container
                    args:
                      - "hello-world"
                    command:
                      - cowsay
                    image: "docker/whalesay:latest"
          parameters:
            - src:
                dependencyName: test-test
                dataKey: body
              dest: spec.containers.0.args.0

In the first event, we are getting an outdated status section with a "healthy" status for the application. However, the application is still not reconciled.
There is no way to distinguish the outdated status section from the new (valid) status section due to missing observedGeneration property.

Describe the solution you'd like
implement observedGeneration in order to compare this property with standard generation property

Describe alternatives you've considered
we tried to find another mechanism to distinguish outdated status section by comparing operationState finishAt and status reconciledAt without success

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[whynowy]

Is this the reason of #1025?

[VaibhavPage]

@whynowy I think both are related

[whynowy]

@tolko - I want to confirm the order with you, did you mean after the EventSource and Sensor were started, there was an Argo-cd Application update, and 2 events were triggered? Or after an Argo-cd Application object update, starting a EventSource trigged 2 actions?