Support setting affinity items

[consideRatio]

We should support setting nodeAffinity, podAffinity, podAntiAffinity, and preferred/required for each.

  affinity:
    nodeAffinity:
      requiredDuringSchedulingIgnoredDuringExecution: # nodeSelector
        nodeSelectorTerms: #
        # logical AND of the items below
        - matchExpressions:
          # local OR of the items below
          - key: kubernetes.io/e2e-az-name
            operator: In
            values:
            - e2e-az1
            - e2e-az2
      preferredDuringSchedulingIgnoredDuringExecution:
      # fullfilled weights summed over and compared in between nodes
      - weight: 1
        preference:
          matchExpressions:
          # local OR of the items below
          - key: another-node-label-key
            operator: In
            values:
            - another-node-label-value

    podAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      # logical AND of the items below
      - labelSelector:
          matchExpressions:
          # logical OR of the items below
          - key: security
            operator: In
            values:
            - S1
        topologyKey: failure-domain.beta.kubernetes.io/zone
      preferredDuringSchedulingIgnoredDuringExecution:
      # sum the weights for each node and compare
      - weight: 100
        podAffinityTerm:
          labelSelector:
            matchExpressions:
            - key: security
              operator: In
              values:
              - S2
          topologyKey: kubernetes.io/hostname

    # Exactly the same fields etc as podAffinity
    podAntiAffinity:
      requiredDuringSchedulingIgnoredDuringExecution:
      - labelSelector:
          matchExpressions:
          - key: app
            operator: In
            values:
            - store
        topologyKey: "kubernetes.io/hostname"
      preferredDuringSchedulingIgnoredDuringExecution:
      - weight: 100
        podAffinityTerm:
          labelSelector:
            matchExpressions:
            - key: security
              operator: In
              values:
              - S2
          topologyKey: kubernetes.io/hostname

[consideRatio]

Can be closed by #239.