Create security tabs hidden behind a feature flag

Why are we doing this work

• cluster vulnerabilities will be shown in a new Security tab for both agent-managed clusters and clusters connected with a certificate

Relevant links

• agent-managed cluster
• cluster connected with a certificate

Non-functional requirements

• Feature flag:
• Testing:

Implementation plan

• backend create cluster_vulnerabilities feature flag
• frontend create Security tab for agent-managed cluster and hide it behind the feature flag at javascripts/clusters/agents/components/show.vue
  • ensure the security tab is the first (and default) tab (before Access Tokens)

~~- [ ] frontend create Security tab for cluster connected with a certificate and hide it behind the feature flag at app/views/clusters/clusters/show.html.haml~~

- ensure the security tab is the third tab