Add support to exclude node labels

[SimonBaeumer]

Currently it is possible to filter node labels with --node-labels.
In reality some nodes have two labels like node-role.kubernetes.io/worker and node-role.kubernetes.io/infra.
To exclude a node with a second label I would like to propose a feature to exclude labels with --exclude-node-labels.

[robscott]

This is a great idea, thanks @SimonBaeumer! Sadly I don't have time to take this on but would welcome any PRs.

[yardenshoham]

@SimonBaeumer how about kube-capacity --node-labels 'node-role.kubernetes.io/worker,!node-role.kubernetes.io/infra'?