Definition of kubernetes events

[alicefr]

Currently, we don't create any kubernetes events, but we could fire an event:
For the BootcNodePool

• when rollout starts and completes
• If the pool goes in degraded state, like there is a node conflict or there in an invalid spec
• There is a new version of the tagged image and this triggers a rollout
• Rollout is halted
  For the BoocNode when a node:
• is in staging
• is in staged
• is rebooting

The events should always be fired by the controller and not by the daemon, in this way we keep the daemon simple and we can limit the RBAC to the event to the controller only.