add observedGeneration to represent Component and AppConfig has reconciled

[wonderflow]

observedGeneration field of status in K8s object is widely used in K8s built-in resource. It reflects the generation of the most recently observed Object.

With the help of observedGeneration field, user can recognize whether a CR is reconciled by controller.

A workflow will like below:

apiversion: core.oam.dev/v1alpha2
kind: Component
metadata:
  name: c1
  generation: 1
spec:
  workload:
    image: nginx:v1
    ...

After the controller reconciled, the observedGeneration will appear and align with generation in metadata:

apiversion: core.oam.dev/v1alpha2
kind: Component
metadata:
  name: c1
  generation: 1
spec:
  workload:
    image: nginx:v1
    ...
status:
  observedGeneration: 1

Later, we have another change, it will be:

apiversion: core.oam.dev/v1alpha2
kind: Component
metadata:
  name: c1
  generation: 2
spec:
  workload:
    image: nginx:v2
    ...
status:
  observedGeneration: 1

And after reconciled, it will be:

apiversion: core.oam.dev/v1alpha2
kind: Component
metadata:
  name: c1
  generation: 2
spec:
  workload:
    image: nginx:v2
    ...
status:
  observedGeneration: 2

Also, CR of AppConfig also need to add this field.

[LeoLiuYan]

/assign

[wonderflow]

@LeoLiuYan Thanks

[wonderflow]

This is a kindly ping. Hi @LeoLiuYan, have you started?

[LeoLiuYan]

This is a kindly ping. Hi @LeoLiuYan, have you started?

Oh.. not yet. I will start in this weekend.

[wonderflow]

@LeoLiuYan Hi, are you still interested on this work？

[LeoLiuYan]

@LeoLiuYan Hi, are you still interested on this work？

Yes, I will submit a PR as soon as possible.

[Ghostbaby]

/assign @Ghostbaby