Add node-labeling charm config using the LabelMaker library

[addyess]

Applicable spec: https://warthogs.atlassian.net/browse/KU-325

Overview

Allows for charm config to label worker and control-plane nodes

Rationale

Allows a juju administrator to specify certain node labels so that dependent workloads can run on properly labeled kubelets. Will need access to the kubeconfig via #22

Juju Events Changes

N/A

Module Changes

N/A

Library Changes

Addition of the node-label library

• LabelMaker provides a path to alternate optional kubectl charmed-kubernetes/layer-kubernetes-node-base#11

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)

[kwmonroe]

Nice!