Collect metadata about nodes

[jandegen]

User story

1. As a developer
2. I want / need to collect detailed information about all nodes in the Kubernetes cluster
3. So that this information can be retrieved from the frontend later

Acceptance criteria

• The proxy collects the metadata name
• The proxy collects NodeStatus (Addresses and heartbeats)
• Current & absolute CPU and RAM usage are collected
• Current & absolute number of pods is collected
• Metadata is persisted in the database

Additional notes

Definition of done (DoD)

• Colours match with color scheme
• Implementation is unit tested
• Code documentation updated (jsdoc or godoc?)
• Changes to database documented at Confluence- Database scheme
• Changes to architecture documented at Confluence - Architecture

DoD general criteria

• Feature has been fully implemented
• All acceptance criteria were met
• Product owner approved features
• All tests are passing
• Pull request to "develop" branch is merged & closed
• Bill of materials is updated with new dependencies