[FluxCD Integration] Support to manage FluxCD Application

**Target**:

sync the underlying helmreleases.helm.toolkit.fluxcd.io and kustomize.toolkit.fluxcd.io CRD with a New gitops.kubesphere.io/v1alpha1/Application CRD

**Task**:
- [x] #679
- [x] #717
- [x] #718
- [x] #767
- [x] #777
- [ ] #740
- [ ] #802

Start with the target: sync the FluxCD HelmRelease and Kustomize CRDs with a new gitops.kubesphere.io/v1alpha1/Application CRD. Review the completed and outstanding tasks listed in the issue, especially #740 and #802, before defining the remaining scope. Done means the underlying CRDs are managed through the Application CRD.

Written by the indexing model from the issue text.