Events: get spot price from bid-advisor

[vgunapati]

Fixes #71

We will get the latest price from bid-advisor to avoid stale ASG spot price,

Problem:

When we are already running spot, if we switch instance type on ASG the events are still getting old instance type spot price

Before: ( Switch m5.xl to m5.2xl )

13m         Normal   SpotRecommendationGiven   spotpriceinfo/eks-vgu-k8s-instance-manager-nodes   {"apiVersion":"v1alpha1","spotPrice":"0.192", "useSpot": true}
8m          Normal   SpotRecommendationGiven   spotpriceinfo/eks-vgu-k8s-instance-manager-nodes   {"apiVersion":"v1alpha1","spotPrice":"0.192", "useSpot": true}
2m59s       Normal   SpotRecommendationGiven   spotpriceinfo/eks-vgu-k8s-instance-manager-nodes   {"apiVersion":"v1alpha1","spotPrice":"0.192", "useSpot": true}

After this change: ( Switch m5.xl to m5.2xl )

11m         Normal   SpotRecommendationGiven    spotpriceinfo/eks-vgu-k8s-instance-manager-nodes  {"apiVersion":"v1alpha1","spotPrice":"0.192", "useSpot": true}
5m6s        Normal   SpotRecommendationGiven    spotpriceinfo/eks-vgu-k8s-instance-manager-nodes  {"apiVersion":"v1alpha1","spotPrice":"0.384", "useSpot": true}
5s          Normal   SpotRecommendationGiven    spotpriceinfo/eks-vgu-k8s-instance-manager-nodes  {"apiVersion":"v1alpha1","spotPrice":"0.384", "useSpot": true}

Testing without EventOnly Mode:

• unit-tests
• Verified that switching from on-demand to spot instances work as expected.
• Verified that switching from spot to on-demand instances work as expected.