Show specific aggregations in each overview

[phildree]

User story

1. As a user
2. I need aggregated information in each view
3. So that I can get information about the lower levels of the hierarchy

Acceptance criteria

• Show previously existing aggregations in the element preview
  • Cluster view: show number of tenants and number namespaces
  • Tenant view: show number of namespaces and number of topics
  • Namespace view: show number of topics

Definition of done (DoD)

• Feature is done when the acceptance criteria are fullfiled
• Feature is done when there are test where it is necessary and they pass
• Feature is done when the linter passes
• Feature is done when it is merged onto our main branch (after the code has been reviewed by at least one other person)
• Feature is done when the code has been documentend or commented properly

DoD general criteria

• Feature has been fully implemented
• Feature has been merged into the mainline
• All acceptance criteria were met
• Product owner approved features
• All tests are passing
• Developers agreed to release