Watch for changes of objects managed by App CR and trigger App reconcile immediately

**Describe the problem/challenge you have**
[A description of the current challenge that you are experiencing.]
Reconciling App CR will create/update objects in the K8s cluster. The reconciling will be triggered with the internal specified by App.spec.syncPeriod. If the objects (e.g. StorageClass, StatefulSet) are updated by the users or become not ready due to some reason before next App reconcile, App CR is not aware of it and still has the condition ReconcileSucceeded with True status.

**Describe the solution you'd like**
[A clear and concise description of what you want to happen. If applicable a visual representation of the UX.]
I'd like to let kapp-controller watch for changes of objects managed by App CR and trigger App reconcile immediately. These changes could be Delete event for an Object or "Ready"/"Not Ready" status change for an Object.

Not sure if it's possible to find the corresponding App CR from the kapp labels of an Object.
```
kind: Pod
metadata
labels:
kapp.k14s.io/app: "1675317921176715845"
kapp.k14s.io/association: v1.783a26fd34e0d185b8884f5d0b46f024
```

**Anything else you would like to add:**
[Additional information that will assist in solving the issue.]

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