feat(kubernetes): add scaling-up/down node-group states (#246)

Author: kangasta

CHANGELOG.md

@@ -8,6 +8,7 @@ See updating [Changelog example here](https://keepachangelog.com/en/1.0.0/)
 ### Added
 - client functions `NewDefaultHTTPClient` and `NewDefaultHTTPTransport` to provide HTTP client default properties
 - kubernetes: experimental support for deleting nodes from node groups
+- kubernetes: consts for `scaling-up` and `scaling-down` node-group states
 
 ### Changed
 - `service.GetKubernetesNodeGroup` method to return `upcloud.KubernetesNodeGroupDetails` type which is extended version of the previous `upcloud.KubernetesNodeGroup`

upcloud/kubernetes.go

@@ -10,6 +10,8 @@ const (
 
 	KubernetesNodeGroupStatePending     KubernetesNodeGroupState = "pending"
 	KubernetesNodeGroupStateRunning     KubernetesNodeGroupState = "running"
+	KubernetesNodeGroupStateScalingUp   KubernetesNodeGroupState = "scaling-up"
+	KubernetesNodeGroupStateScalingDown KubernetesNodeGroupState = "scaling-down"
 	KubernetesNodeGroupStateTerminating KubernetesNodeGroupState = "terminating"
 	KubernetesNodeGroupStateFailed      KubernetesNodeGroupState = "failed"
 	KubernetesNodeGroupStateUnknown     KubernetesNodeGroupState = "unknown"