Add gray release support

[LinuxSuRen]

You can get the release strategy list via: ks get --all-namespaces strategy. Below is an example:

apiVersion: servicemesh.kubesphere.io/v1alpha2
kind: Strategy
metadata:
  annotations:
    app.kubernetes.io/icon: /assets/bookinfo.svg
    kubesphere.io/creator: admin
    servicemesh.kubesphere.io/newWorkloadName: details-v2
    servicemesh.kubesphere.io/oldWorkloadName: details-v1
    servicemesh.kubesphere.io/workloadReplicas: "1"
    servicemesh.kubesphere.io/workloadType: deployments
  creationTimestamp: "2021-03-15T05:43:22Z"
  generation: 1
  labels:
    app: details
    app.kubernetes.io/name: bookinfo
    app.kubernetes.io/version: v1
  name: blue-test-1
  namespace: ks
  ownerReferences:
  - apiVersion: app.k8s.io/v1beta1
    blockOwnerDeletion: true
    controller: false
    kind: Application
    name: bookinfo
    uid: 8eb1bbec-d44f-4d5f-8507-500e92775234
  resourceVersion: "152221"
  selfLink: /apis/servicemesh.kubesphere.io/v1alpha2/namespaces/ks/strategies/blue-test-1
  uid: 2ca3bc16-1e91-4cc5-b200-e9630bd2fac0
spec:
  governor: v1
  hosts: details
  principal: v1
  protocol: http
  selector:
    matchLabels:
      app: details
      app.kubernetes.io/name: bookinfo
      app.kubernetes.io/version: v1
  strategyPolicy: WaitForWorkloadReady
  template:
    spec:
      hosts:
      - details
      http:
      - route:
        - destination:
            host: details
            subset: v1
          weight: 100
        - destination:
            host: details
            subset: "1"
          weight: 0
  type: Bluegreen