Automated Kubernetes version updates

[m1ghtym0]

Feature

Make the Kubernetes version of a Constellation cluster upgradable with zero downtime.
For more info see the RFC

• Automatically fetch hashes for Kubernetes artifacts
• Download and verify Kubernetes components with hashes
• Extend the JoinService for automatic updates
• Annotate nodes with their Kubernetes components hash
• Create a upgrade agent for automatic updates
• Add Support for Kubernetes components inside the Constellation node operator
• Expose Kubernetes cluster version in NodeVersion
• Reconcile the Kubernetes cluster version
• Add k8s upgrades to CLI

[derpsteb]

Included in: https://github.com/edgelesssys/constellation/releases/tag/v2.6.0