Add add kf connector button

[buehlefs]

Description

Add add kafka faas connector button to be able to add new connectors without dragging links from topics. This allows apps that only use topics and kafka faas connectors to be build in the UI.

• [ ] this PR contains breaking changes!

Resolves / is related to

What is affected by this PR

• [ ] Backend
  • [ ] Kubernetes logic
  • [ ] Domain model
• [ ] API
  • [ ] discussed changes in the team / informed the team about changes
  • [ ] updated insertTestValues.sh and Postman Collections are updated
• [x] Frontend
  • [ ] Ensure that it is compilable for production (npm run build -- --prod)
• [ ] Documentation

Checklist

• [ ] Ensure that new source files include the license header
• [ ] Ensure JavaDoc is up to date