feat: Add labels on Application's k8s events (#11381)

[svghadi]

Closes #11381

This PR implements #11381 enhancement to expose application labels on k8s events generated by Argo CD.

Change:
This PR introduces a new key resource.eventLabelKeys in argocd-cm configmap which takes in a comma separated string of label keys. For any events generated for Applications containing the specified label keys from argocd-cm, the controller adds the matched label onto the event thus establishing an easy link between the event and the application to filter-out/process later using labels.

The specified label keys are matched against the Application and it's AppProject labels. In case of conflict between labels on Application and it's AppProject, the Application label values are prioritised and added to the event.

Sample output:

$ kubectl get events -l env=dev --show-labels
LAST SEEN   TYPE     REASON               OBJECT                                      MESSAGE                                                                LABELS
25s         Normal   ResourceCreated      application/test-labels-on-app-k8s-events   admin created application                                              app=test,env=dev
25s         Normal   OperationStarted     application/test-labels-on-app-k8s-events   admin initiated sync to  (7e2013dcfdd0c801eececd38aa5f3db898e29f4b)    app=test,env=dev
24s         Normal   OperationCompleted   application/test-labels-on-app-k8s-events   Sync operation to 7e2013dcfdd0c801eececd38aa5f3db898e29f4b succeeded   app=test,env=dev
24s         Normal   ResourceUpdated      application/test-labels-on-app-k8s-events   Updated sync status:  -> Synced                                        app=test,env=dev
24s         Normal   ResourceUpdated      application/test-labels-on-app-k8s-events   Updated health status:  -> Progressing                                 app=test,env=dev
17s         Normal   ResourceUpdated      application/test-labels-on-app-k8s-events   Updated health status: Progressing -> Healthy                          app=test,env=dev

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[todaywasawesome]

Wdyt about resource.includeLabelKeys and resource.excludeLabelKeys could have wildcards as an improvement - @leoluz

[todaywasawesome]

I think this is a great start, to make it feature complete can we handle the include/exclude use cases?